2125 sort tasks refactor

I refactored the Activetasks. 

I was able to delete far more code than adding new code (even with the whitepsace removals and code formatting) and implementing new stuff that operates on the collection should now get pretty straightforward. 

I separated the remove whitespace commit and another one, but I can squash / rebase.

Here is what I did:
- do not use a model as a kind of collection, directly operate on the
  collection which gets filtered for the view
- remove the view DataSection which acted as layer to fetch collections from
  the model and passed it to a view
- remove not used html-template
- format code

This is the base for COUCHDB-2125  but the feature might need some concept and style which could take some time