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