core: reset blank template CPU profile

Although blank template resides in default cluster (probably because
of db restrictions), it shouldn't be linked to any CPU profile.

This causes any VM created in other Cluster than default, to have wrong
CPU profile (derived from template).

Change-Id: I383dac119e38a2c1d1d313ce738ecbf900612293
Bug-Url: https://bugzilla.redhat.com/1084930
Signed-off-by: Gilad Chaplik <gchaplik@redhat.com>
core: reset CPU profile when changing VM cluster

Since CPU profile is coupled to cluster, when changing a cluster
the 'old' CPU profile is invalid.
The edit VM command will validate a right profile for
new cluster.

Change-Id: I10ce4aa64ffddf500f11c89bb942d9abbac8cf31
Bug-Url: https://bugzilla.redhat.com/1084930
Signed-off-by: Gilad Chaplik <gchaplik@redhat.com>