* 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
* Second websocket channel for the projector
* Removed use of projector requirements for REST API requests.
Refactored data serializing for projector websocket connection.
* Refactor the way that the projector autoupdate get its data.
* Fixed missing assignment slide title for hidden items.
* Release all items for item list slide and list of speakers slide. Fixed error with motion workflow.
* Created CollectionElement class which helps to handle autoupdate.
Uses django channels instead of tornado for the autoupdate. Therefore
tornado is nolonger a dependency of OpenSlides (but channels).
This uses websockets instead of SockJS.
Use the flag insecure in the start command to provide static files serving.
Use a new session backend that has a ForeignKey to User.
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.
Added api for groups.
Refactored serializers now using 'id' instead of 'url'.
Rework of tornado autoupdate functionality.
Implemented extra data in SockJS messages.
* 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
- Added missing insertpre plugin and allow <pre> tag with class
attribute. Added font style to base.css.
- Removed unused link to old ckeditor.css (now managed by
django-ckeditor).
