Add ability to remove unplaced units
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
Clear ECS as well as db
fix failling test
Clean up object notation
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.
Standardize constraint inputs across the GUI.
Allow dropping units on the root container of a machine.
Removing superfluous this.remove()
Merge pull request #529 from jaycee/place-on-root-container

Allow dropping units on the root container of a machine.

The changes to block dropping unplaced units on deleted machines broke the check for dropping on an existing container; this corrects that check so dropping on a not deleted root container works.
Address QA issues.
Test fixes.
Remove the provider test results per #1339751
Disable containerization when not supported.
Because MBs are important.
Merge pull request #531 from frankban/disable-containers

Disable containerization when not supported.

Implement an infrastructure to dynamically disable
containers support in the machine view based on the
environment's provider type.

A list of supported containers is defined at
environment level, and used to check containerization
support.

Avoid hard-coding the list of container types in the
create machine view.

Update the service unit token to accept a list of
available container types.
Also removed the env from the service usint token:
it doesn't appear to be used at all.

This branch also includes some drive-by fixes to
methods' docstrings and comments.