SPARK-1352: Improve robustness of spark-submit script

1. Better error messages when required arguments are missing.
2. Support for unit testing cases where presented arguments are invalid.
3. Bug fix: Only use environment varaibles when they are set (otherwise will cause NPE).
4. A verbose mode to aid debugging.
5. Visibility of several variables is set to private.
6. Deprecation warning for existing scripts.

Author: Patrick Wendell <pwendell@gmail.com>

Closes #271 from pwendell/spark-submit and squashes the following commits:

9146def [Patrick Wendell] SPARK-1352: Improve robustness of spark-submit script
[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
SPARK-1376. In the yarn-cluster submitter, rename "args" option to "arg"

Author: Sandy Ryza <sandy@cloudera.com>

Closes #279 from sryza/sandy-spark-1376 and squashes the following commits:

d8aebfa [Sandy Ryza] SPARK-1376. In the yarn-cluster submitter, rename "args" option to "arg"
[SPARK-1377] Upgrade Jetty to 8.1.14v20131031

Previous version was 7.6.8v20121106. The only difference between Jetty 7 and Jetty 8 is that the former uses Servlet API 2.5, while the latter uses Servlet API 3.0.

Author: Andrew Or <andrewor14@gmail.com>

Closes #280 from andrewor14/jetty-upgrade and squashes the following commits:

dd57104 [Andrew Or] Merge github.com:apache/spark into jetty-upgrade
e75fa85 [Andrew Or] Upgrade Jetty to 8.1.14v20131031
[Hot Fix #42] Persisted RDD disappears on storage page if re-used

If a previously persisted RDD is re-used, its information disappears from the Storage page.

This is because the tasks associated with re-using the RDD do not report the RDD's blocks as updated (which is correct). On stage submit, however, we overwrite any existing information regarding that RDD with a fresh one, whether or not the information for the RDD already exists.

Author: Andrew Or <andrewor14@gmail.com>

Closes #281 from andrewor14/ui-storage-fix and squashes the following commits:

408585a [Andrew Or] Fix storage UI bug