ISPN-4544 BaseWordCountMapReduceTest#testCombinerForDistributedReductionWithException doesn't actually test reduce exception

Fix test failure DistributedTwoNodesMapReduceTest.testCombinerForDistributedReductionWithException
Allow creation of Infinispan caches as OSGI managed service
ISPN-4818 Allow creation of Infinispan caches as OSGi managed service

Add checkstyle plugin and correspoding clean-ups.
ISPN-4818 Allow creation of Infinispan caches as OSGi managed service

Add integration tests some fixes and clean-up.