Add support for grouping to Infinispan subsystem

Enable setting of groups in Infinispan subsystem. More information about grouping can be found at https://docs.jboss.org/author/display/ISPN/The+Grouping+API.

It should be possible to enable it as well as set a grouper class. The following is respective configuration for standalone Infinispan.

<clustering>
  <hash>
     <groups enabled="true">
        <grouper class="com.acme.KXGrouper" />
     </groups>
  </hash>
</clustering>