GIRAPH-650: Exception in GiraphConfiguration initialization (majakabiljo)
GIRAPH-653: Hadoop_non_secure broken (majakabiljo)
GIRAPH-639: Add support for multiple Vertex/Edge inputs (majakabiljo)
Merge remote-tracking branch 'origin/trunk' into hive-tests

Conflicts:
	giraph-core/src/main/java/org/apache/giraph/io/internal/WrappedVertexOutputFormat.java
	giraph-hive/src/main/java/org/apache/giraph/hive/HiveGiraphRunner.java