ofagent: merge br-tun into br-int

Highlights:
- Deprecate br-tun.
- Reduce the use of OFPP_NORMAL action.  Use mac address info
  obtained from get_device_details and l2-pop to reduce flooding.
- Use OpenFlow metadata instead of "internal" VLANs.
  Now tenant networks are VLAN transparent.

Implements: blueprint ofagent-port-monitor
Implements: blueprint ofagent-merge-bridges
Change-Id: I21ee1c6d141863182b487e10c7bfe911b1a472ab
Merge "ofagent: merge br-tun into br-int"