adding bin/setup_midonet_topology.py, to be used by devstack/lib/quantum_thirdparty/midonet

This is related to issue#2 in midokura/devstack
https://github.com/midokura/devstack/issues/2
Fixing setup_midonet_topology.py by renaming quantum --> neutron.

This file should be in sync with the same file in the midokura/devstack repo.

Signed-off-by: Alex Vasilyev <avasilyev@midokura.jp>
Merge pull request #35 from midokura/av-mido/devstackIssue2

Adding file bin/setup_midonet_topology.py, and fixing it for the neutron rename.