Drive by cleanup.
Don't re-render panel when hiding notification.

All we need is to clear the notification, so stick to that.
Usability tweak to improve notifications.
Merge pull request #313 from kadams54/fix-deployer-notifications

### QA

To test:

1. Drag and drop the first charm.
2. Click the Deploy button and verify the summary is correct, but don't confirm. Cancel or close the summary.
3. Drag and drop the second charm.
4. Click the Deploy button - used to be you'd get a "no uncommitted changes" message. Now you'll now see the expected list of two services and two units.
Prototype.
Tests and lint pass.
Merge pull request #314 from makyo/unit-placement

QA in sandbox:

- disable the simulator;
- drag/deploy a service;
- get a reference to the new service unit:
  `var unit = app.db.units.item(0)`;
- add a new machine to the db:
  `var machine = app.db.machines.add({id: 'new1'})`;
- add the new machine to the ECS
  attaching a callback that will remove the ghost machine:
  `app.env.addMachines([{}], function() {app.db.machines.remove(machine)}, {modelId: 'new1'})`;
- add a new container to the machine:
  `var container = app.db.machines.add({id: 'new1/lxc/0'})`
- add the new container to the ECS
  attaching a callback that will remove the ghost machine:
  `app.env.addMachines([{parentId: 'new1', containerType: 'lxc'}], function() {app.db.machines.remove(container)}, {modelId: 'new1/lxc/0'})`
- place the unit in the container:
  `app.env.placeUnit(unit, 'new1/lxc/0')`
- click deploy and confirm (status bar);
- everything should work.

Perform QA in real env, also make sure placing units on root-level machines works