STORM-211: Add module for HDFS integration

More information on usage, etc. is available in the README.md.


I thought about making 'rotationAction' a single instance as opposed to a list, and providing a MultiRotationAction implementation that essentially does the same thing.

That seemed like overkill to me so I kept it simple.

The idea behind allowing more than one is basically "who knows what people will do with this, so let's give them freedom, and hope the don't shoot themselves in the foot."

Right now, rotation actions run in-line with tuple processing. So they need to be kept light/fast depending on the settings.