Add a rake task to automatically restart foreman when changes occur

Created by: jubianchi

Particularly useful when working on gitlab (I personally use the GitLab Development Kit), this adds a rake task to start foreman along with a watcher on some files to automatically restart processes when changes occur.

I had to update a bunch of gems due to a version conflict on listen. The test suite is OK on my local machine.

I don't know if it more appropriate to leave this here or to move it in the GDK. It seemed to me to be a good thing to put this task here as not everyone will use the dev. kit.