(captiveportal, new) add cleansing of input templates to remove all non-changed data from the user provided template.

Next stepts to implement,
	make fetch_template aware of the user templates, so the frontend fetch will return the right content.
	deploy user provided template on service reload

Shuffled three of them back to status for the last round of
fire bombing before 15.7.17.  This is not going to be in the
stable version, but I want to have this ready for development
version feedback.  This is so much nicer without the tick
wrapping of tabs and pills and what not...

While there, improve the logic for writing error messages for
log files, e.g. clog files would never be empty.  ;)

The captive portal is being replaced!  This hooks up the
new page into the services section while ditching most of
the old code.  There'll be no migration, if you use package
`opnsense-devel' and the captive portal you'll have to switch
to `opnsense' or migrate to the new code.  Beware that the
new captive portal is going to be a huge step forward but
features will trickle in week after week until it is stable
enough to merge it.  Latest release date is going to be 16.1.

not fully sure if we should place them in service section, they maybe moved to settings later on.

PR: https://forum.opnsense.org/index.php?topic=1490.0

This one and the former were good ideas, but:

o They only affected a very small percentage of the actual code, and
o Reviewing changes is best done in the config.xml, not the revision message.