OVS plugin: add tunnel ips to central database

OVS plugin: add tunnel ips to central database

bp simplify-ovs-tunnel-mgmt

Makes the OVS plugin agent report its own IP address to the centralized
quantum database, and build its set of tunnels based on the contents of
this centralized database.  This removes the need for a removes need for
a 'remote-ips' file on each compute node that needs to be updated
when a new host is added.

Also:
- simplifies error handling within tunnel manager daemon_loop
- fixes issues with operational status not working for tunnel-mode
- fixes issue that not-stripping vlan of tunneled packet potentially
crashes OVS, causing flows to get wiped.

Change-Id: I4d285669e29beecf745fe620581fa6bc332a446c