Add support for executing Distributed Tasks and MapReduce updates

radargun-1.1.xsd
	Updated XSD file for changed stages

Utils.java
	Add method to invoke public methods with a String parameter on an
object to allow passing parameters from the RadarGun stage to a
MapReduce or Callable object
	
MapReduceCapable.java
MapReduceStage.java
InfinispanMapReduceWrapper.com
	Add support for passing parameters to Mapper, Reducer, and Collator
objects
	
Infinispan52MapReduceWrapper.com
	Override membersCount() method to conform to the Infinispan 5.2 API
	
DistributedTaskCapable.java
DistributedTaskStage.java
InfinispanDistributedTaskWrapper.java
	Add support for executing a Callable object against the cache