GIRAPH-665: Reduce ZooKeeper output in tests by changing log level from INFO to ERROR (aching)
GIRAPH-666: Netty execs threads and metrics threads don't get
cleaned up properly (aching)
GIRAPH-608: Spelling error in Combiner.java (Michael Aro via aching)
GIRAPH-667: Decouple Vertex data and Computation, make Computation and Combiner classes switchable  (majakabiljo)
GIRAPH-620: Website Documentation: How to use Hive I/O with Giraph (nitay)
GIRAPH-669: Streamline home page (apresta)
GIRAPH-512: JavaDoc warnings (emre.aladag via nitay)
Merge remote-tracking branch 'upstream/trunk' into trunk

Conflicts:
	giraph-core/src/main/java/org/apache/giraph/job/GiraphConfigurationValidator.java