Spark 1246 add min max to stat counter

Here's the addition of min and max to statscounter.py and min and max methods to rdd.py.

Author: Dan McClary <dan.mcclary@gmail.com>

Closes #144 from dwmclary/SPARK-1246-add-min-max-to-stat-counter and squashes the following commits:

fd3fd4b [Dan McClary] fixed  error, updated test
82cde0e [Dan McClary] flipped incorrectly assigned inf values in StatCounter
5d96799 [Dan McClary] added max and min to StatCounter repr for pyspark
21dd366 [Dan McClary] added max and min to StatCounter output, updated doc
1a97558 [Dan McClary] added max and min to StatCounter output, updated doc
a5c13b0 [Dan McClary] Added min and max to Scala and Java RDD, added min and max to StatCounter
ed67136 [Dan McClary] broke min/max out into separate transaction, added to rdd.py
1e7056d [Dan McClary] added underscore to getBucket
37a7dea [Dan McClary] cleaned up boundaries for histogram -- uses real min/max when buckets are derived
29981f2 [Dan McClary] fixed indentation on doctest comment
eaf89d9 [Dan McClary] added correct doctest for histogram
4916016 [Dan McClary] added histogram method, added max and min to statscounter
Revert "SPARK-1236 - Upgrade Jetty to 9.1.3.v20140225."

This reverts commit ca4bf8c572c2f70b484830f1db414b5073744ab6.

Jetty 9 requires JDK7 which is probably not a dependency we want to bump right now. Before Spark 1.0 we should consider upgrading to Jetty 8. However, in the mean time to ease some pain let's revert this. Sorry for not catching this during the initial review. cc/ @rxin

Author: Patrick Wendell <pwendell@gmail.com>

Closes #167 from pwendell/jetty-revert and squashes the following commits:

811b1c5 [Patrick Wendell] Revert "SPARK-1236 - Upgrade Jetty to 9.1.3.v20140225."