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>