Remove redundant javascript code.

The json javascript structure is already populated and passed to the view
from the IndexController.
Add slicer revision input box and hide unused release selector

Moving forward, we could probably add some link (4.2.2-1, 4.3.0, ..)
that would populate the input box with the appropriate revision value.
Merge pull request #33 from jcfr/add-slicer-revision-to-regular-layout

Add slicer revision to regular layout