Dragging and dropping an unplaced unit to the root container now updates the icons on the machine and root container
Machine and container tokens are properly rendered with their tokens when the machine view is first instantiated and rendered
When units are added into the database they now update the parents machine token
Root container units are now shown on deploy
Fixed failing tests and added additional tests for new token rendering functionality.
Merge pull request #524 from hatched/fix-machine-token-icons

Fix machine token icon rendering issues

Placed token icons do not render properly under multiple situations. This fixes the following issues:

 - Switching away then back to mv fixes the machine token rendering issues but only renders the root container and unit.
 - Machine token doesn't get updated to show the units on deploy.
 - Root container doesn't get updated properly on deploy wrt placed units.

Persisting issues - These issues will not be resolved until a refactor of the token rendering code post 1.0:
- Container tokens disappear when deployed then reappear with the unit token properly rendered.
- Unit icons in the machine tokens disappear then reappear a few seconds later with the ack from juju.
Allow dropping units on the root container of a machine.