SPARK-1167: Remove metrics-ganglia from default build due to LGPL issues...

This patch removes Ganglia integration from the default build. It
allows users willing to link against LGPL code to use Ganglia
by adding build flags or linking against a new Spark artifact called
spark-ganglia-lgpl.

This brings Spark in line with the Apache policy on LGPL code
enumerated here:

https://www.apache.org/legal/3party.html#options-optional

Author: Patrick Wendell <pwendell@gmail.com>

Closes #108 from pwendell/ganglia and squashes the following commits:

326712a [Patrick Wendell] Responding to review feedback
5f28ee4 [Patrick Wendell] SPARK-1167: Remove metrics-ganglia from default build due to LGPL issues.
SPARK-1064

This reopens PR 649 from incubator-spark against the new repo

Author: Sandy Ryza <sandy@cloudera.com>

Closes #102 from sryza/sandy-spark-1064 and squashes the following commits:

270e490 [Sandy Ryza] Handle different application classpath variables in different versions
88b04e0 [Sandy Ryza] SPARK-1064. Make it possible to run on YARN without bundling Hadoop jars in Spark assembly
Spark-1163, Added missing Python RDD functions

Author: prabinb <prabin.banka@imaginea.com>

Closes #92 from prabinb/python-api-rdd and squashes the following commits:

51129ca [prabinb] Added missing Python RDD functions Added __repr__ function to StorageLevel class. Added doctest for RDD.getStorageLevel().
Add support for running pipe tasks is separate directories