Simple PageRank algorithm implementation in Python for SPARK-760
Use new Configuration() instead of new JobConf() for ObjectWritable.

JobConf's constructor loads default config files in some verisons of
Hadoop, which is quite slow, and we only need the Configuration object
to pass the correct ClassLoader.
Changed yarn.version to 2.0.5 in pom.xml
Change scala.Option to Guava Optional in Java APIs.
Merge pull request #805 from woggle/hadoop-rdd-jobconf

Use new Configuration() instead of slower new JobConf() in SerializableWritable
Code update for Matei's suggestions
Report compressed bytes read when calculating TaskMetrics
Create SparkContext in beforeAll for MLLib tests
This overcomes test failures that occur using Maven
Merge pull request #808 from pwendell/ui_compressed_bytes

Report compressed bytes read when calculating TaskMetrics
Clean up scaladoc in ML Lib.
Also build and copy ML Lib scaladoc in Spark docs build.
Some more minor cleanup with respect to naming, test locations etc.
Removing dead docs
Merge pull request #810 from pwendell/dead_doc_code

Remove now dead code inside of docs
Add MetricsServlet for Spark metrics system
MetricsServlet code refactor according to comments
Add ML Lib scaladoc to API dropdown
Merge pull request #806 from apivovarov/yarn-205

Changed yarn.version to 2.0.5 in pom.xml
Merge pull request #809 from shivaram/sgd-cleanup

Clean up scaladoc in ML Lib.
Fix import organization.
Merge pull request #807 from JoshRosen/guava-optional

Change scala.Option to Guava Optional in Java APIs
Merge pull request #812 from shivaram/maven-mllib-tests

Create SparkContext in beforeAll for MLLib tests