MessageDispatcher obtaining log using getClass() causes issues with subclassing

When subclasses of MessageDispatcher obtain their own log, log4j 2.x wanrs of conflicting message factories because MessageDispatcher uses getClass() to obtain a log instance which may have been initialized elsewhere. The solution is for MessageDispatcher to obtain a log using its own class.

2015-07-21 19:58:45,981 WARN The Logger org.infinispan.remoting.transport.jgroups.CommandAwareRpcDispatcher was created with the message factory org.apache.logging.log4j.message.ParameterizedMessageFactory@18fb808d and is now requested with the message factory org.apache.logging.log4j.message.StringFormatterMessageFactory@6f84895e, which may create log events with unexpected formatting.