SHARK-138: JoinOperator outputs result of standard objects.
Add a test case for SHARK-138.
Merge branch 'master' of github.com:sun-rui/shark

Conflicts:
	src/main/scala/shark/execution/JoinOperator.scala
	src/test/scala/shark/SQLSuite.scala
Merge pull request #137 from rxin/join

Bringing pull request #95 up to the master branch