Additional edits for clarity in the graphx programming guide.
Describe GraphX caching and uncaching in guide
Merge pull request #431 from ankurdave/graphx-caching-doc

Describe caching and uncaching in GraphX programming guide
Merge pull request #424 from jegonzal/GraphXProgrammingGuide

Additional edits for clarity in the graphx programming guide.

Added an overview of the Graph and GraphOps functions and fixed numerous typos.
VertexID -> VertexId
Fixed SVDPlusPlusSuite in Maven build.
Changed SparkConf to not be serializable. And also fixed unit-test log paths in log4j.properties of external modules.
Merge remote-tracking branch 'apache/master' into filestream-fix
Merge pull request #434 from rxin/graphxmaven

Fixed SVDPlusPlusSuite in Maven build.

This should go into 0.9.0 also.
Merge pull request #435 from tdas/filestream-fix

Fixed the flaky tests by making SparkConf not serializable

SparkConf was being serialized with CoGroupedRDD and Aggregator, which somehow caused OptionalJavaException while being deserialized as part of a ShuffleMapTask. SparkConf should not even be serializable (according to conversation with Matei). This change fixes that.

@mateiz @pwendell
Merge pull request #436 from ankurdave/VertexId-case

Rename VertexID -> VertexId in GraphX