(bug 43006) Disable input element and toolbar on saving/removing

Replacing the toolbar with a message (just like for the site links etc.) will be done in another
patch set.

- patch set 2: Moved css to DataValues extension
- patch set 3: rebase
- patch set 4: Disabling property selector and snak type selector
- patch set 5: Moved dis-/enabled methods from entity selector to suggester
- patch set 6: Correctly enabling the toolbar after editing
- patch set 7: Removed obsolete inline comment
- patch set 8: Displaying snak view state via draw() method, removed disable/enable from variation
- patch set 9: rebase
- patch set 10: Add 'ui-state-disabled' class to widget.element, not to sub nodes

Change-Id: I14e89ecc020424518c8256fba70c1f7caa3aedad