stratosphere/stratosphere — pull request #707 by fhueske (2014-04-21 23:19:17+00:00)
Title: Add projection join, join JavaDocs and removes unsupported join methods.

This PR
- adds projection joins as described in the [documentation](http://stratosphere.eu/docs/0.5/programming_guides/java.html#transformations). Unit and integration tests are included.
- adds JavaDocs to the join transformation methods.
- removes unsupported join transformation methods.