core: Activate host doesn't set return value

ActivateVds defacto works but doesn't set the return value to true,
which result REST calls to believe it failed.

Change-Id: Id6802431ebc4239e46ab7df30355e18ebf368e86
Bug-Url: https://bugzilla.redhat.com/1077300
Signed-off-by: Roy Golan <rgolan@redhat.com>
(cherry picked from commit 977a612194013378bc4868f44f9b1ab5170a2453)