Ensure ovsdb-client is stopped when OVS agent dies

If the OVS agent is killed, the interpreter is killed before any cleanup
is done. This patch adds a signal handler for SIGTERM that exits
normally so that the existing cleanup is done and the ovsdb-client
process is terminated.

Change-Id: Ie4f8ff434098100f4699124403d58caa784084cf
Fixes spelling error
Closes-Bug: #1284257

Change-Id: I3c5ff9b7e8830023f54d09d74c1a9d3c9a4b82f5
Merge "Ensure ovsdb-client is stopped when OVS agent dies"
Merge "Fixes spelling error Closes-Bug: #1284257"