[this is a squashed merge from-]

* Install owncoud 9.1 and provide an upgrade path from 8.2. This also disables memcached and goes with apc. The upgrade fails with memcached.

* Remove php apc setting

* Add dav migrations for each user

* Add some comments to the code

* When upgrading owncloud from 8.2.3 to 9.1.0 the backup of 8.2.3 was overwritten when going from 9.0 to 9.1

* Add upgrade path from 8.1.1. Only do an upgrade check if owncloud was previously installed.

* Stop php5-fpm before owncloud upgrade to prevent database locks

* Fix fail2ban tests for owncloud 9

* When upgrading owncloud copy the database to the user-data/owncloud-backup directory

* Remove not need unzip directives during owncloud extraction. Directory is removed beforehand so a normal extraction is fine

* Improve backup of owncloud installation and provide a post installation restore script. Update the owncloud version number to 9.1.1. Update the calendar and contacts apps to the latest versions

* Separate the ownCloud upgrades visually in the console output.