Check for stale PID lock when starting
Check for stale PID lock when starting

The PID lock file does not actually test whether the lock is valid during
acquisition.  This leads to a failure to acquire the lock (essentially just
a file-based lock) when starting the process after a failure / kill.

Change-Id: Iebf0e077377278eb28b3280a8abfc605ac68a759

citrix-openstack/nodepool,seandst/nodepool,citrix-openstack/nodepool,Tesora/tesora-nodepool,Tesora/tesora-nodepool,seandst/nodepool