Fixed and improved docs

- Made docs consistent with Code
- Replaced commands to use cdap-cli
- Updated and tested all commands to work.

Build : https://builds.cask.co/browse/CG-SGUT1-1
Does it make sense to call it PageRankSparkProgram - will help to read and will get immediate attention of those who are looking for how to implement SparkProgam and run in CDAP