OF-1311: Don't assume values are Strings.

OF-1321: Proper null-check to avoid stacktrace with stale session.

By default, the Maven structure uses the Maven artifactId value as the name for a plugin.
Maven artifactIds typically include tokens that will cause problems, such as dashes and dots.
The plugin name is used in various places, that all have limitations: filenames (the jar file
itself, the i18n files), package names (for the java files generated from JSPs), etc.

This commit allows the name of the plugin to be overridden using a maven property 'plugin.name'
and includes instructions on what the best format is.

For plugins to be able to use the tags used in the admin console, the tags should be distributed in a library. By making this library a Maven module, plugins can define the library as a dependency.

Note that the admin.tld file is duplicated, but *slightly* modified in the Maven module: the path of the tags is different (META-INF vs WEB-INF).

The HSQLDB library that ships with Openfire (for Ant) is newer than the
dependency that's defined in Maven. This introduces a compatibility issue
at runtime:

> org.jivesoftware.database.SchemaManager - Unexpected token: FILES in statement [ SET FILES]

The difference is likely an oversight, caused by us taking a very long time
to merge the Maven PR. At the time it was created, the dependency was still okay.

The Avalon framework is a dependency of the Proxool Maven artificat, but was
never included as a library to Openfire prior the move to Maven (so, we can
do without).

The Avalon dependency itself has a dependency of servlet-api 2.3, which is
unwanted, and causes issues when compiling JSPs.

Previously, the openfire-plugin-assembly artifact replaced the default artifact. When using
plugin project as a Maven dependency, this causes oddities: the dependency still is a JAR file,
but does not conform to a standard archive. This results in missing classes. Instead, this commit
retains the original project artifact. This is expected to be more useful.

Sadly, we appear to can pick only one of these options:

- Attach the openfire-plugin-assembly artifact (making it referencable)
- Define a finalName for this artifact (<artifactname>.plugin)

Both options appear to be mutually exclusive.

More annoyance is prevented by giving the plugin jar file a 'proper' name, I suspect, which is why
I opted for doing that. For the other option, set 'appendAssemblyId' to true, and remove the
'attach' element of the 'make-assembly' block.

The removed openfire-plugin-jar assembly does not appear to have a practical purpose: it builds a
jar file that is pretty similar to the standard artifact (it misses some metadata, and its final
name is different). Removing this assembly reduces complexity, at the cost of a benefit that I
cannot see.

The build plans for the plugins should not inherit from the parent project, as this
ties their existence in with our parent project. Third party developers cannot do
this (without modifying the parent project structure). We should facilitate third
party developers, and use the same tools as we provide them.

This commit removes the parent/child dependencies between the top-level parent POM
and the plugins POM. There still as a parent/child dependency between the plugins
POM and each individual plugin.

Although I'm not sure this change is a complete solution, it is aimed to more closely
represent a development setup in which a third party developer might find itself. To
create a plugin of their own, they can now:

 - Use our 'plugins' module directly (define it as a parent)
 - Replace our 'plugins' module by a proprietary one (when developing multiple
   proprietary plugins).
 - Take most POM definition from our 'plugins' module and merge that with a new
   stand-alone plugin project.

Straightforward failure to escape in this debugging plugin.

* Add option to disable delayed delivery (XEP-0203)

This fixes some encoding issues, preventing LDAP users that have an '@' character in their username from becoming admin.

In an annoying quest to reproduce a bug related to JSTL and plugins I completely redid the MoTD plugin admin console page. I added CSRF protection to justify my changes.

Never did reproduce that bug...

* OF-1311: Allow lists to be stored in a property.

* OF-1312: Allow SASL mechanisms to be configured in the admin console.

A new property (ldap.encodeMultibyteCharacters) is introduced that controls if multibyte characters in LDAP search queries are escaped.

Escaping of these characters started with the fix for OF-830, which appears to have caused OF-1305. Although I can't say that escaping of characters is wrong (per RFC 4515), it does cause real-world problems.

This fix defaults to not encoding again (reverting back to the behavior pre OF-830, without affecting other changes made in OF-830).

RestAPI plugin, synchronizing invalid room state when creating a room in a clustered Openfire

When creating a room using RestAPI plugin, RoomUpdateEvent should be fired only after the room is fully processed/configured

* run `mvn versions:set -DnewVersion=4.2.0-SNAPSHOT`
* manually edited non-included plugins

This commit introduces some dependencies that were added to Openfire since the original Maven stucture was build. With these, the Maven build should compile again.

(dwr has transitive dependency to it)

The Maven structure is:
-/
--dbutil (used by xmppserver)
--i18n (used by starter and xmppserver)
--starter (launcher and starter package, startup.jar)
--xmppserver (nearly everything in the src dir, openfire.jar)
--webadmin (admin plugin)
--plugins
---broadcast
---...

I've also added Maven plugins to mimic partial behavior of the Ant build (copying dependencies, bin/conf folder, ...)

This commit addresses issues OF-546.

I reconfigured the pom.xmls to work with the existing directory structure, (instead of default src/main/java), so that the current src folder stays untouched.

What it can do:
- Run tests successfully
- Generate JavaDoc
- Assemble most plugin jars (without JSP)
- Assemble admin plugin (without JSP)
- Generate a source zip/tar.gz for distribution (as the download page offers it currently)
- Build the startup.jar and openfire.jar, copy it in the right directory, so that Openfire can be run with `java -jar startup.jar`

What it can't do:
- Build executables for every platform (e.g. install4j, *.dmg, ...)
- Build some plugins (e.g. ofmeet) due to non-Maven dependencies.

Todos:
- Fix these issues
- Move source code to the correct paths, e.g. /src to xmppserver/src/main/java

This was referenced by Openfire as dbutil.jar, but because this cannot be referenced via Maven Central, we add it as module for Openfire.

* OF-1299 / OF-1300: Fixes for XML Debugger plugin.

Causes the plugin to print the remote address, as well as less 'garbage' (compressed and/or encrypted data).