Create network-utils element

Creates a new network-utils element which currently contains a
single utility that can be used to create an ovs bridge. This is
being split out from init-neutron-ovs so that it can be used as a
stand alone script in ci.

Change-Id: I8c7bc6bb9db3417811d567a48b6b3a2c628f5ccd
Merge "Create network-utils element"