Update to Django 1.6
Some more template fixes:

- Fixed #992 (Use correct countdown format)
- Fixed #909 (Backend und projector template style)
  * Search bar with same border-radius like login button.
  * Projector: Fixed overlay message style. Allow HTML code (use template filter 'safe').
  * Dashboard: Tooltips, Buttons and Widget fixes.
- Fixed template does not exists error if custom slide is activated.
- Countdown: Add css to show negative countdown in red.
- Add missing translation strings to English po file (for transifex).
Merge pull request #1009 from emanuelschuetze/1.5c1-fixes

Template fixes
Update English translation files.
Merge pull request #1001 from ostcar/django1.6

Update to Django 1.6
Merge pull request #1026 from normanjaeckel/EnglishTransFile

Update English translation files.
Updated translations (DE, PT, CS).
Merge pull request #1028 from emanuelschuetze/translations

Updated translations (DE, PT, CS).
Move run_tornado import into runserver function because its imports needs settings (new in Django 1.6).
Use encoded string for insert in sys.path and print during main script. Fix #1022.
Merge pull request #1029 from normanjaeckel/RepairDjangoUpdate

Move run_tornado import into runserver function because its imports need...
Merge pull request #1024 from normanjaeckel/FixUnicodeEncodeError

Use encoded string for insert in sys.path during main script. Fix #1022.
Updated changelog for 1.5b2.
Merge pull request #1030 from emanuelschuetze/changelog

Updated changelog for 1.5b2.
Release 1.5b2
Update version to 1.5c1-dev
Merge pull request #1033 from emanuelschuetze/1.5b2-release

1.5b2 release