Try to erase file whenever app exits. Also never exit cleanly

This is to prevent attacks where the registrar is dead, but the
address file still remains. An attacker can start a new process
at the port/host specified on the address file and intercept
requests from clients.

This is a rather minor attack, and they can't really obtain
anything at that time (unless someone tries to do anything
that involves passing them the secret key). Also since we never
exit cleanly, the grid engine will restart the registrar fast
enough anyway, and overwrite the addressfile. So the window
for a successful attack is small, and the booty is also very
tiny. Worst they can do with even the secret key is to send
some prank messages by inserting things, or cleaning it out.
Easily recognizable and fixable by just changing the secret.

In short, I'm probably thinking too much about this. This is
probably secure enough. <- Famous Last Words

Change-Id: I01a735f6e386bb8120473e91315d1920477b54d1