fullstack: Use ovs-2.5 for tests
fullstack: Use ovs-2.5 for tests

The commit bumps commit in 2.5 branch for current HEAD. It contains fix
for local VXLAN bug [1] that blocked us in running fullstack tests.

[1] http://openvswitch.org/pipermail/discuss/2016-July/022122.html

Change-Id: I41bd7b084ffb4d6e7082ba01629f5b64a5a94419

sebrandon1/neutron,noironetworks/neutron,eayunstack/neutron,openstack/neutron,cloudbase/neutron,sebrandon1/neutron,igor-toga/local-snat,openstack/neutron,mahak/neutron,huntxu/neutron,huntxu/neutron,openstack/neutron,mahak/neutron,cloudbase/neutron,noironetworks/neutron,eayunstack/neutron,igor-toga/local-snat,mahak/neutron