Fix inconsistency between Nova-Net and Neutron

The neutron client raises NeutronClientException (status_code 404)
that is not unknown for nova, and is translated in 500 computeFault.
Catching this exception in nova/nova/network/neutronv2/api.py and
raising more generic exception as exception.NotFound solves the problem.

Added also an unitary test to test neutronv2 api

bug #1160309
bug #1200175

(cherry picked from commit 4a2915b4e389bfba0ff25583369fd75b24e19118)

Conflicts:
	nova/network/quantumv2/api.py

Change-Id: Ib2f1a0d49a12114b28f0cd5ce0bb7119f864d1a6
Ensure anti affinity scheduling works

The query for the group in the system_metadata would not correctly
filter the instances with the groups.

Fixes bug: 1218878

Conflicts:
        nova/db/sqlalchemy/api.py
        nova/tests/db/test_db_api.py

Change-Id: I623c73635c36ffa038ae01476a25ba0c0863e536
(cherry picked from commit 4233e16ba2f5bb85e93494b6eeb9ffff31dbdf30)
Merge "Fix inconsistency between Nova-Net and Neutron" into stable/grizzly
Merge "Ensure anti affinity scheduling works" into stable/grizzly
Merge branch 'stable/grizzly' of https://github.com/openstack/nova into grizzly/stable