Use key --> List<Tuple> instead of key --> Tuple for HashCache; add HashJoinInfo to define hash-join structure
Add hashjoin runtime impl
Add hashjoin runtime impl
Merge branch 'iss20'
Add hashjoin runtime impl
Merge branch 'iss20'

Conflicts:
	src/main/java/com/salesforce/phoenix/coprocessor/UngroupedAggregateRegionObserver.java
Merge pull request #339 from maryannxue/master

issue #20 : Runtime part implementation