GIRAPH-704: Specialized message stores (majakabiljo)
GIRAPH-705: Type converters and giraph-hive cleanup (nitay)
Merge remote-tracking branch 'origin/trunk' into jython-scripts

Conflicts:
	giraph-core/src/main/java/org/apache/giraph/benchmark/PageRankBenchmark.java
	giraph-core/src/main/java/org/apache/giraph/jython/JythonUtils.java
	giraph-core/src/main/java/org/apache/giraph/utils/ConfigurationUtils.java
	giraph-core/src/test/java/org/apache/giraph/jython/TestJython.java