Added ability to change the deployer bar height mode.
Merge pull request #400 from huwshimi/popover-controls

Added ability to change the deployer bar height mode

Added height mode controls to the deployer bar.

QA:
- drag a charm to the canvas
- click "2 changes" in the deployer bar
- in the top right there will be three height mode icons, clicking on those should change the height of the open panel
- click on "deploy"
- clicking on the height mode controls for the summary panel should again change the height