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
It doesn't look like you're styling these spans based on these classes so I would prefer they move to an attribute, which you can then key off of instead of making a bunch of `hasClass()` requests.

This function could then read something like:
```
_setModeFromTarget: function(e) {
  this._setMode(e.currentTarget.getData('deployer-size'));
}
```

Or probably drop this function all together and just call the `_setMode()` method from the click handler.