F actor groups

A lot of improvements in DND-code, especially to handle DND-views inside other DND-views.

- Actors in Groups are now their own view elements
- Views can have several settings -> https://github.com/transparencyint/CGIP/blob/f-actor-groups/app/views/view.js#L5
- the new-actor element is now a draggable as well and finally works (#75)
- removed and restructured a lot of code
- a lot of bug fixes (some Heisenbugs in there)

In order to test, you again have to create a group manually in the DB as described here: https://github.com/transparencyint/CGIP/pull/81

No screenshots since nothing visually changed.