Adds service unit icons to machine and token containers.

QA:
Deploy a fairly big bundle, and wait awhile for it to create new machines
and containers.

Go to machine view--machine tokens should have a service unit icon.

Click around the machine tokens--some of them should have LXCs, and these
should be rendered as container tokens, with icons for their units.

All machines should show at least one container token for the "bare metal".

Known issues:
* This doesn't have a ton of tests--I welcome pointers on how to test some of 
  this, and request you let me land those tests as follow ups.
* The machine token only renders an icon for the first unit on it--it should
  update to also show the icons on containers as they're added, but we need to 
  fix the update cycle for that, and will do so in a follow up.