GIRAPH-696: Should be able to spill giraph metrics to a specified directory on HDFS
GIRAPH-697: Clean up message stores (majakabiljo)
GIRAPH-693: Giraph-Hive check user code as soon as possible (nitay)
wip
Merge remote-tracking branch 'origin/trunk' into hive-auto

Conflicts:
	giraph-hive/src/main/java/org/apache/giraph/hive/common/HiveUtils.java
	giraph-hive/src/main/java/org/apache/giraph/hive/output/HiveVertexWriter.java
	giraph-hive/src/main/java/org/apache/giraph/hive/output/VertexToHive.java
	pom.xml
GIRAPH-688: Make sure Giraph builds against all compatible YARN-enabled Hadoop versions, warns if none set, works w/new 1.1.0 line (ereisman)
GIRAPH-: Simplify Giraph Hive I/O
Merge remote-tracking branch 'origin/trunk' into hive-auto