Move the patch_neutron function in the utils file

We need to patch neutron in both devstack and the job that build
the neutron-icehouse deb package. We need to move that function
outside of the akanda file so that we can reuse it.

Change-Id: I0469f3954c4edea30a6dba33fed80d36aafd2390
Signed-off-by: Rosario Di Somma <rosario.disomma@dreamhost.com>