Fixed some (pdf) template issues and updated (DE) translation.

- Fixed #737 (Motion edit link is missing for normal delegate users)
- Fixed motion pdf filename errors (now use motion-<identifier>.pdf or if no identifier: motion-<title>.pdf with using djangos slugify for special chars in title)
- Fixed motion pdf build error if there is an unauthorized version
- Enlarge max_length of event name field to 50 chars.
- Align participant import instruction with motion import page.
- Added title field to particpants-demo_en.csv.
- participant overview: Show comma after last_name only if first_name and last_name are given.
- Changed all page titles to "<specific action page> - <event-name>" (moved event-name to the end of the string)
- Updated EN tranlation string.
- Updated DE translations.
Merge pull request #740 from emanuelschuetze/template-fixes

Fixed some (pdf) template issues and updated (DE) translation.
Change the Workflow of a motion in CreateView.

The Manager can choose the workflow in the createview. The default value
is the workflow from the config.

In the UpdateView the workflow in which the motion is, is choosen by
default.

The workflow will only be reset, if it is changed.