fix(controller): format command before creating container

The self._command_announceable() check was called inline with code
that formatted the container's command, so no announcer would be
created since the command showed up as "start {c_type}" literally.
The _command property is only referenced in this code.
test(controller): add regression test for "start {c_type}" bug
Merge pull request #1285 from deis/hotfix-app-announcers

fix(controller): format command before creating container