Fix Bug 1783 RO does not create management networks where appropriate

If there is mgmt-network in the descriptor,
there is no mapping of that network to a VIM network in the descriptor,
also there is no mapping in the "--config" parameter or at VIM creation;
that mgmt-network will be created.

Change-Id: Ifbd86c3aaf9db2c7d7455ed6e81c1cbcd1f227c7
Signed-off-by: aticig <gulsum.atici@canonical.com>