fix(scheduler/container): Ephemeral Containers for Applications

Currently the Applications are launched using stateful containers, ie they
do not automatically die when they are killed. This PR makes them ephemereal
when they are launched so they are destroyed once done with.
same reason as other places. better to let docker have the responsibility of cleaning it up. we can probably remove the [ExecStop line](https://github.com/deis/deis/pull/1425/files#diff-530a37eb84d4183cb52cef27ecce6694R228) ?