Fixed #957 (Allow list-style in CKEditor)

Allowed additional css styles 'color' and 'background-color'
for span html fields in ck-editor (and bleach).
Merge pull request #1018 from emanuelschuetze/fix957

Extend css style optinos in CKEditor
add missing license html6lib-python
Merge pull request #1020 from DerPate/fix_licens

Add html5lib-python license.
Template improvements.

- motion detail template: Fixes motion manage state template block.
- mediafile list template: Fixed missing activeline class.
- item detail template: Fixed is_active_slide conditions.
- assignment view template: Use bottongroup instead of single radio buttons.
- Projector template: Updated header and countdown style. Removed footer.
- Added config options to show logo and/or title/description.
- Projector template: New config options to set background color and font color for projector header.
- Make WLAN form labels not translateable.
Merge pull request #1019 from emanuelschuetze/several-1.5-fixes

Template improvements and translation strings
Use encoded string for insert in sys.path during main script. Fix #1022.