Feature/rails 4 fix

Move vendor/assets -> app/assets because of [Rails 4](https://github.com/rails/rails/pull/7968)

Fixed `update_projekktor` rake task, because the projekktor file structure seems to have been changed.

Did not update Projekktor Core because I ran into a Projekktor bug ["projekktor extTypes[fileExt] is undefined"](http://www.projekktor.com/board/index.php?id=34042, that does not seem to be fixed yet.