Merge pull request #11 from shivaram/master

Search rLibDir in worker before libPaths
Merge pull request #15 from shivaram/master

Remove Apache Staging repo and update README
Add linear_solver_mnist to examples/.
Merge pull request #20 from concretevitamin/digit-ex

Add linear_solver_mnist to examples/.
Merge pull request #22 from shivaram/master

Add support for passing Spark environment vars
Fixes for using SparkR with Hadoop2.
1. Exclude ASM, Netty from Hadoop similar to Spark.
2. Concat services files to ensure HDFS filesystems work.
3. Update README with an example