Call foreman-stop before starting foreman

In the event of a zombie or stuck process, send a kill signal to known
processes before re-starting foreman processes.

This helps to smooth out the application booting process using foreman
Merge branch 'master' into add_foreman_stop_to_foreman_start
Merge pull request #657 from Tahi-project/add_foreman_stop_to_foreman_start

Call foreman-stop before starting foreman