Motion identifier setting and versioning.

Now the view decides, whether to setup a new version or not. Automatic identifier setting is the default. Also some fixes of the motion save method.
Merge pull request #638 from normanjaeckel/MotionRework

Motion identifier setting and versioning.
Merge pull request #650 from emanuelschuetze/template-improvements

Template improvements
Some more template improvements
- Better config icon.
- Renamed media to files (only for GUI).
- Add datatable function for motion and asssignemnt overview table. Removed old filter/sorting code.
- Some more template styling work.
Updated translation.