Rewind buffer before converting to String

Otherwise, you end up writing nothing to the cache
Wrapper that should handle API changes for Infinispan 6.0
Added plugin for Hazelcast 3.x
Updated Hazelcast 2.x version to 2.6
Removed code duplication and changed hazelcast 3 version
Add JDG 6.2 plugin
update schema
add leveldb cachestore dependency only in special profile
pom-links.xml synced with pom.xml (missing hazelcast3)
Old configuration API removed from Infinispan 6.0
* Add ProvidesMemoryOverhead feature to provide byte overhead for storing cache values
* RandomDataStage
** allow the memory overhead to be set or retrieved from the wrapper featuring ProvidesMemoryOverhead
** allow specifying the total data size, and letting the stage calculate the number of values to put into the cache.
** log the number of words used to generate the string data
* MapReduceStage
** add a parameter to print the result map and object
** ensure that the payload string is always set
Various changes in key generators and value checkers:
* CheckDataStage can check data from StressTest (generally), local mode is supported
* PersistentStorageCapable can force memory-only read (used in CheckDataStage)
* StressTestStage.loadAllKeys = in shared mode all nodes should load all keys
* Added key generator for keys that can carry variable amount of random data (mitigating bigger keys)