Make vdsm-tool dynamic module loading take the package name into account

According to the imp.load_module API documentation:
    http://docs.python.org/2/library/imp.html#imp.load_module
the name that is passed as a first parameter should be the full
module name, i.e., including the package name. Without the package
name, relative imports and future proofing of the module are not
possible.

Change-Id: I432d2f31f5e9f58c942a2cca334ca4bc39995c7d
Signed-off-by: Antoni S. Puimedon <asegurap@redhat.com>
Reviewed-on: http://gerrit.ovirt.org/20762
Reviewed-by: Dan Kenigsberg <danken@redhat.com>