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 seems to be a depth-first approach: Datasets -> create -> URIs -> descriptors -> DatasetWriter. I think that made sense in the old guide where the API was the only entry point and the first task was to get a dataset and put data in, but I'm not sure I would use the same organization here.

I think it would make more sense with this outline:
* Dataset
** URIs
** Descriptors
* Datasets methods
** load
** create (with links to DatasetWriter and other ways of adding data)
** update
** delete
* Working with a Dataset
** Avro objects
** DatasetWriter
** DatasetReader