[SQL] Rewrite join implementation to allow streaming of one relation.

Before we were materializing everything in memory.  This also uses the projection interface so will be easier to plug in code gen (its ported from that branch).

@rxin @liancheng

Author: Michael Armbrust <michael@databricks.com>

Closes #250 from marmbrus/hashJoin and squashes the following commits:

1ad873e [Michael Armbrust] Change hasNext logic back to the correct version.
8e6f2a2 [Michael Armbrust] Review comments.
1e9fb63 [Michael Armbrust] style
bc0cb84 [Michael Armbrust] Rewrite join implementation to allow streaming of one relation.
SPARK-1365 [HOTFIX] Fix RateLimitedOutputStream test

This test needs to be fixed. It currently depends on Thread.sleep() having exact-timing
semantics, which is not a valid assumption.

Author: Patrick Wendell <pwendell@gmail.com>

Closes #277 from pwendell/rate-limited-stream and squashes the following commits:

6c0ff81 [Patrick Wendell] SPARK-1365: Fix RateLimitedOutputStream test
Fix storage UI bug