Created a fictional 'User Profile' example in cdk.data.hbase.avro.example.
This example demonstrates basic put, get, scanner functionality, as well as
using Composite DAOs and optimistic concurrency control.

The models for the example are in src/main/avro/example-models of the
cdk-data-hbase module. To run this example, a valid hbase-site.xml
should be on the classpath that specifies an HBase cluster. The example
will register a schema and create the required tables automatically.
Introduce DatasetAccessor
A Dataset implementation backed by HBase.
Store entity as full entity, not stripped of key fields. This avoids a costly merge.
Make AvroUtils.mergeSpecificStringTypes respect fields in key schema.
Support Avro Specific in addition to Generic.