core: Allow Update of Network on Host

This patch removes the canDoAction that checks
whether a network that is being updated is used
by one of the data center hosts.

This creates uniform behaviour, since removing
a network that is used by a host from a data center
is allowed.

Change-Id: If328c80571d404be453a83c6a14396716b678c74
Bug-Url: https://bugzilla.redhat.com/909820
Signed-off-by: Muli Salem <msalem@redhat.com>