avocado.utils.virt: Disable virt if remote module is off

Signed-off-by: Ruda Moura <rmoura@redhat.com>
avocado.utils.remote: Log when module is disabled.

Log message if remote or virt module is off.

Signed-off-by: Ruda Moura <rmoura@redhat.com>
Merge pull request #99 from ruda/virt_off_if_remote_off

Virt off if remote off