restapi: Added usages option to CLI add cluster network

When adding a network via CLI, in cluster context, added the ability to
pass the usages option - same as when updating a network.

Change-Id: Id4573674ddd1015eba33a05b95d687f685f707c4
Bug-Url: https://bugzilla.redhat.com/show_bug.cgi?id=949884
Signed-off-by: Lior Vernia <lvernia@redhat.com>