fix(Column Resizing): Only compile elm if added

The resizeLeft and resizeRight elements were being $compiled whether or
not they were added to the DOM with prepend()/append(). This worked for
some reason with jQuery but without jQuery present angular was failing
with exceptions at calls to insertBefore() because it was looking for
element.parent and an unattached element has no parent.

Fixes #1684, #1655
fix(Column Resizing): Fix broken tests w/ uids

New column UID generation broke the column resizing tests because the
column classes had changed.

This change:

1. Adds a new resetUids() method to gridUtil that will reset the UID index
to 000.
2. Add tests for uid generation and resetting.
3. Updates the column resizing tests to account for the UID change.