UI: Error message is shown when app is deleted while it's not running

[tiff]

If your app is not running and you delete it, an error message is shown but the app is correctly destroyed.

Debugging:

root@f440e7063907:/tmp# curl -i --data "name=app-name" http://app-manager/destroy
HTTP/1.1 500 Internal Server Error
Content-Type: application/json; charset=UTF-8
Date: Mon, 03 Aug 2015 12:13:37 GMT
Content-Length: 410

"Error response from daemon: no such id: 4cfdfd84a01587454400f1bde185b09bb00bf6b20fad9f1e13d1a3994d3e58c5\ntime=\"2015-08-03T12:13:37Z\" level=fatal msg=\"Error: failed to stop one or more containers\" \nError response from daemon: no such id: 4cfdfd84a01587454400f1bde185b09bb00bf6b20fad9f1e13d1a3994d3e58c5\ntime=\"2015-08-03T12:13:37Z\" level=fatal msg=\"Error: failed to remove one or more containers\" \n"