Add containers creation to the simulator.
Merge pull request #273 from frankban/machine-simulator

QA:
- make devel;
- deploy a large bundle (e.g. openstack) 
  so that more units are likely to be added
  by the simulator;
- wait a minute or two;
- in the JS console, run the following:
  `app.db.machines.map(function(machine) {return machine.id});`
- ensure containers have been correctly added.