Task table body is now rendered as a CollectionView.

Reasons for doing so:
* Learning CollectionViews.
* Cleaner DOM, with less script tags around tr.
  See next bullet point why that may be good.
* I think it will be easier to implement
  drag/sort when it is a collection view.
Found small shortcut on class name bindings.
Reimplemented when keyDown and double click events are handled.

We had two views before, now we have only one.
Merge branch 'master' into pg-sql