Added symmetrical parameter on cs_order

Pacemaker resource ordering by default is symmetrical. However, in some cases ordering should only apply to the starting of resources and not stopping, for which symmetrical=false can be set on a resource. Cs_order now does this automatically (default true), so it's also backwards compatible.

More info about ordering: http://clusterlabs.org/doc/en-US/Pacemaker/1.0/html/Pacemaker_Explained/s-resource-ordering.html .