Initial commit of adding histogram functionality to the DoubleRDDFunctions.
Add tests for the Java implementation.
CR feedback
Remove extranious type definitions from inside of tests
Remove extranious type declerations
Replace magic lengths with constants in PySpark.

Write the length of the accumulators section up-front rather
than terminating it with a negative length.  I find this
easier to read.
Remove Pickle-wrapping of Java objects in PySpark.

If we support custom serializers, the Python
worker will know what type of input to expect,
so we won't need to wrap Tuple2 and Strings into
pickled tuples and strings.
Add graphite sink for metrics

This adds a metrics sink for graphite.  The sink must
be configured with the host and port of a graphite node
and optionally may be configured with a prefix that will
be prepended to all metrics that are sent to graphite.
Add custom serializer support to PySpark.

For now, this only adds MarshalSerializer, but it lays the groundwork
for other supporting custom serializers.  Many of these mechanisms
can also be used to support deserialization of different data formats
sent by Java, such as data encoded by MsgPack.

This also fixes a bug in SparkContext.union().
Send PySpark commands as bytes insetad of strings.
FramedSerializer: _dumps => dumps, _loads => loads.
Simple cleanup on Spark's Scala code while testing core and yarn modules:
-) Remove some of unused imports as I found them
-) Remove ";" in the imports statements
-) Remove () at the end of method call like size that does not have size effect.
Merge pull request #178 from hsaputra/simplecleanupcode

Simple cleanup on Spark's Scala code

Simple cleanup on Spark's Scala code while testing some modules:
-) Remove some of unused imports as I found them
-) Remove ";" in the imports statements
-) Remove () at the end of method calls like size that does not have size effect.
correct number of tasks in ExecutorsUI
Slightly enhanced PrimitiveVector:
1. Added trim() method
2. Added size method.
3. Renamed getUnderlyingArray to array.
4. Minor documentation update.
rename "a" to "statusId"
Return the vector itself for trim and resize method in PrimitiveVector.
Add PrimitiveVectorSuite and fix bug in resize()
Merge pull request #3 from aarondav/pv-test

Add PrimitiveVectorSuite and fix bug in resize()
Merge pull request #182 from rxin/vector

Slightly enhanced PrimitiveVector:

1. Added trim() method
2. Added size method.
3. Renamed getUnderlyingArray to array.
4. Minor documentation update.