ISPN-4528 Genericize remaining M/R internal classes

Master only. See https://issues.jboss.org/browse/ISPN-4528 for more details. 
Oracle JDK 7. Here is the error:
[ERROR] COMPILATION ERROR : 
[INFO] -------------------------------------------------------------
[ERROR] /Users/vblagoje/workspace/infinispan/core/src/main/java/org/infinispan/distexec/mapreduce/MapReduceManagerImpl.java:[709,21] method asSet in class org.infinispan.commons.util.Util cannot be applied to given types;
  required: T[]
  found: java.lang.Class<org.infinispan.distexec.mapreduce.MapReduceManagerImpl.DeltaList>
  reason: argument type java.lang.Class<org.infinispan.distexec.mapreduce.MapReduceManagerImpl.DeltaList> does not conform to vararg element type java.lang.Class<? extends org.infinispan.distexec.mapreduce.MapReduceManagerImpl.DeltaList<DE>>