Add a WebHDFS backend manager
Explain the different HDFS backends for the OrionHDFSSink, and explain how WebHDFS works
Fix markdown in the README and add a correspondence between HDFS backends and the port they use
Fix markdown in the README and add a correspondence between HDFS backends and the port they use
Merge pull request #22 from telefonicaid/feature/20

Add a WebHDFS backend manager