Revert "Convert the clara_manager script into a daemon"

This reverts commit 0811e5dabdb99fe3ca393e3094b84fcbdae953c5.

No need to use the python-daemon package to convert the clara-manager
script into a daemon. Upstart does it nicely with almost no effort [1].

[1]: http://lincolnloop.com/blog/joy-upstart/
Catch signals to proper exit
Fix stop all processes when a process is killed

When a process is killed an exception is raised (killing a process
should not be needed, ideally all Clara processes should terminate
nicely). The exception was not caught and some of the process were never
requested to stop.

Fix this by catching the exception inside the loop, so all the processes
are stopped.
Provision clara-manager service

- Use Upstart to ensure the service is running.
- Ensure service restart if the configuration file changes.
Forward listening port of clara-manager service