Add setMOMPolicyParameters

This adds setMOMPolicyParameters to the API and a configuration
option mom/tuning_policy to the configuration file.

It is intended to be used for fine tuning a MoM policy.

Change-Id: Ie2c2fce24a8a499976ef845ce1e7e40bdd439949
Signed-off-by: Martin Sivak <msivak@redhat.com>
Reviewed-on: http://gerrit.ovirt.org/16659
Reviewed-by: Dan Kenigsberg <danken@redhat.com>