bin: add the host to a specific cluster

Fix bz #1059950 - Ask the user which cluster to use. Default cluster is
'Default' if exists. Otherwise, the default is engine_api.clusters.list()[0]

Change-Id: I00167e70296645e5cf732b64d87efa1cf66ca783
Signed-off-by: Meital Bourvine <mbourvin@redhat.com>
Signed-off-by: Sandro Bonazzola <sbonazzo@redhat.com>
Bug-Url: http://bugzilla.redhat.com/1059950
Bug-Url: http://bugzilla.redhat.com/1043906