Moving Kite Dataset API info from old guide per CDK-753.

Link to the old guide from which this came. This is just shards of information brought forward so they're not lost. This info should be woven into the samples before 1.0.

http://kitesdk.org/docs/current/kite-data/guide.html
This is focused on storage, but the point we want to make is about interaction within a program. In a program that works with Kite, Avro's object model is used, even though the Avro format might not be (when storing to Parquet or HBase).

In this introduction, the record instances that are returned are defined by Avro, specifically Avro's generic data classes. Regardless of the underlying storage format, Kite uses Avro's object model so that applications can be written once and changing the underlying storage format is as simple as switching the dataset URI.

Kite also supports Avro's specific and reflect object models. (Add links to more info on using those) Specific records are java classes generated from an Avro schema. Reflect objects are regular java objects and classes that Avro can work with through reflection.