Enable debug logging in q-agt output

when only q-agt is used, without q-svc, typically in a multi-host config, q-agt wasn't logging debug output.
This change enable debug output, as it's done for q-l3, q-dhcp or q-meta agent.

Change-Id: I1f49cf9994fa9cfbaa166dac8d4e713ba99c5674
Fixes: bug #1166775
Merge "Enable debug logging in q-agt output"