Made the mass-scale-up UI in the machine view show unplaced units
mass scale-up UI in machine view now displays and is functional for the ghost services.
Added tests for new scale-up functionality
Prevent default on stopHover

* Use the existing `_ignore` method in the mv drop target extension in both
  start _and_ stop.
* Tests and test updates.
Merge pull request #431 from jaycee/firefox-mv-dragndrop-404

Fix the bad request in firefox on machine token drag and drop placement.

* We already call `_ignore` for the `_startHover` function--we need it on stop
  as well.
Merge pull request #430 from hatched/show-scaled-up-unplaced

Show scaled-up unplaced units.

Mass-scaled-up unplaced units now show in the unplaced units column and are placable.
Ghost services can now be scaled up using the mass-scale-up UI in the machine view.