Merge branch 'master' into zheilbron/asterix_issue470

Conflicts:
	asterix-algebra/src/main/java/edu/uci/ics/asterix/algebra/operators/physical/InvertedIndexPOperator.java
	asterix-app/src/main/java/edu/uci/ics/asterix/file/DatasetOperations.java
	asterix-app/src/main/java/edu/uci/ics/asterix/file/IndexOperations.java
	asterix-app/src/main/java/edu/uci/ics/asterix/file/SecondaryBTreeCreator.java
	asterix-app/src/main/java/edu/uci/ics/asterix/file/SecondaryIndexCreator.java
	asterix-app/src/main/java/edu/uci/ics/asterix/file/SecondaryInvertedIndexCreator.java
	asterix-app/src/main/java/edu/uci/ics/asterix/file/SecondaryRTreeCreator.java
	asterix-metadata/src/main/java/edu/uci/ics/asterix/metadata/declared/AqlMetadataProvider.java