Map based Adsdimension demo

A Map based implementation Adsdimensions Demo, following parts are implemented
- A generic mechanism to specify schema for input. We still need to come up with a way to send the schema to
  DimensionComputation and HDSOutOperator. Sasha is working on that.
- A Map based aggregator to be used with DimensionComputation.
- A Serializer which serializes keys and values to be used with HDS, and reconstruct these from byte array.
- A QueryOperator to retrives data from cache as well HDS for give key.
- A sample Demo Application.

Sample Demo application is in working state.
Here is where key order could be guaranteed.