Some template fixes and improvements:

- Fixed absoluteurl in motion detail template. Renamed '_edit' to '_update'.
- Fixed wrong projector link ind assigment poll template.
- Improved assignment projector slide.
- Fixed #884: Add PDF note to translation string "Show paragraph numbering"
Merge pull request #905 from emanuelschuetze/projector-fixes

Fixes and improvements for projector and template
pylint check for the projector app
Use flake8 instead of pep8. Orderd the imports with isort

* changed the fab-command pep8 to check
* checked and fixed any code with flake8. Also the urls.py