core: Use version 3.0 instead of 2.2 UpdateVmCommandTest

Uses version 3.0 instead of 2.2 for minimal supported cluster level
version in UpdateVmCommandTest.

Change-Id: I7caebd147a47e1874e3327ce99df4a2de25c51f0
Bug-Url: https://bugzilla.redhat.com/1127590
Signed-off-by: Martin Perina <mperina@redhat.com>