Fixed missing creation time of motion version.
Show now string if identifier is not set set (in widgets and motion detail).
Merge pull request #869 from emanuelschuetze/1.4.2-fixes

Fixes for motion version and identifier
Merge remote-tracking branch 'openslides/stable/1.4.x'
Rework of the projector with websocket

* Set a static projector title
* absolute_urls for the activate links
* update the projector when a slide changes (in save())
* insert the absolute_url template filter
* Preview to slides
* renamed is_active to is_active_slide