Fixed deployer bar change notifications
Refresh list of unplaced units on DB updates.
Merge pull request #311 from mitechie/qa-deployer-bar-fixes

Landing for Huw and pr/310
Merge pull request #305 from kadams54/unplaced-units-render

### QA

With `/:flags:/il/mv/`, switch to the machine view. Select a charm in the browser and then click on "Add to my canvas". When the details panel closes, you should see the unplaced service sitting in the Unplaced Units column.