Optimize query in _select_dhcp_ips_for_network_ids

Only query the DB for relevant columns instead of
all of the port columns.

 Conflicts:
        neutron/db/securitygroups_rpc_base.py

Partial-Bug: #1373851
(cherry picked from commit 8d430a7f2e903dda06d8d75d6abcd63423c4c0a1)

Change-Id: I32cd4a0bc6799ce77cea13188676308e3e641d19
BSN: Set inconsistency record on delete failure

Set a bad value in the consistency DB on a delete
failure so a sync is triggered the next time the backend
servers become available.

This fixes the issue where the backend servers are unavailable
when an object is deleted from ML2 but not deleted from the
backend.

Conflicts:
	neutron/tests/unit/bigswitch/test_servermanager.py

Closes-Bug: #1377350
Change-Id: I24713a03af4d3499645241f900de1f572689c235
(cherry picked from commit e9f001a63a555f067c4567a88613d14853442524)
Merge "Optimize query in _select_dhcp_ips_for_network_ids" into stable/icehouse
Merge "BSN: Set inconsistency record on delete failure" into stable/icehouse
Merge branch 'stable/icehouse' of https://github.com/openstack/quantum into stable/icehouse

Conflicts:
	neutron/plugins/bigswitch/servermanager.py
	neutron/tests/unit/bigswitch/test_servermanager.py