Fix #490: Item editor buttons for media files fixed for Django 1.6
flake8-clean the code a bit

We still have a few ignored error codes and excluded folders left.
Fix occurrences of E126
Merge branch 'master' into next

* master:
  Fix occurrences of E126
  flake8-clean the code a bit
  Fix #490: Item editor buttons for media files fixed for Django 1.6