Fix Bug 1782 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: Ic4c1e9bc8399a220cba4f2a490519a5fd7893a73
Signed-off-by: aticig <gulsum.atici@canonical.com>