supervisor.exec_config only returns completion deferred - no tests

job id is created and manged by _Job.
Create mocked group
adding to pool from job caller - no tests

After discussing with @cyli, we decided to change pool addition in this
branch itself. Now, all the callers of _Job and _DeleteJob will get
deferred and will add it to the pool
started tests
DeferredPool has __contains__
execute_launch_config shorter tests

using FakeSupervisor and FakeJob
supervisor lint fixes
Merge branch 'master' into job-synchronous

Conflicts:
	otter/test/test_supervisor.py
_Job tests and other tests pass
checking delete deferred in pool
Merge pull request #648 from rackerlabs/job-synchronous

AS-285: Jobs finish after update (review)