XD-282 A first iteration for the Dataset support to store POJOs with Avr...

Adding the datastore Avro support based on CDK

Depends on Cloudera CDK for now - will switch to new dependency once in place

Uses Hadoop 2.0.5 for now - CDK code needs some v2 classes/methods - will be able to change this with new dependency hopefully

Will follow up with sink support next