* Add caching support to users/group
* Add a function has_perm that works with the cache.
* Removed our session backend so other session backends (without the database) can be used
* Add is_present field for csv import of users.
* Refactor JS functions get_full_name and get_short_name (Fixes#2136).
- Show participant number in get_full_name() output.
- Sort users by first or last name.
- Extend config option to sort users.
- Mark unused Python methods get_short_name and get_full_name.
Added custom slide projector element class.
Added welcome slide as custom slide.
Added user slide projector element class.
Added clock, countdown ans message projector elements.
Renamed SignalConnectMetaClass classmethod get_all_objects to get_all (private API).
Added migrations to core app.
Fixed and wrote tests.
Updated CHANGELOG.
Added motion creation view, motion update view, version permit and delete view, view to support motions, view to set and reset state. Refactored motion submitters and supporters.
Also added the derective osPerms to check if the current user has permissions.
Removed old Django views and urls for user.
Created utils.views.APIView which should be used instead of the AjaxView.
Fixes: #1470Fixes: #1454
Refactored user creation and update via REST API. Used new serializer.
Cleaned up management commands, signals and imports. Moved code from 'api.py' to 'models.py'.
Changed usage of group 'Registered'. Now the users don't have to be members to gain its permissions. Used customized auth backend for this.
Added and changed some tests.
* seperate unittests and integration tests
* moved old tests in seperat folder 'old'
* created a testrunner that does not create a testdatabase, if only unittests are run
* wrote some unit- and integration tests as examples
* fixed user.get_short_name() to use the sort order from config
* fixed wrong url_pattern in the user app
