Allow ordering of cs_groups

Cs_order only supported ordering of cs_primitives, but groups can also be ordered in Pacemaker. To allow this, an extra parameter was added to the cs_order which allows you to specify you're dealing with groups. This way, autorequire works as you would expect.

Example:

````
cs_group {
    'group_name_1': ... ;
    'group_name_2': ... ;
}
cs_order {
    'o_g1_before_g2':
        first   => 'group_name_1',
        second  => 'group_name_2',
        resources_type => 'cs_group';
}
````