- while upgrading a host, throw a HOST_OFFLINE ("Server could not be contacted") exception if the host can no longer be resolved (instead of HANDLE_INVALID)
- also corrected the parameters of the HANDLE_INVALID exception, as an extra parameter is needed for the friendly error name.
- in the UpdateManualHostPlanAction class I replaced Host with the private property _host in several places, so we are no longer trying to resolve the host each time we want to write something into logs
- added some null checks, to avoid reporting null reference exception
Signed-off-by: Mihaela Stoica <mihaela.stoica@citrix.com>