CDK-94. Create CDK runtime convenience Maven dependencies

This is an extension of Ryan's work on https://github.com/kite-sdk/kite/pull/78. See https://issues.cloudera.org/browse/CDK-94

Avro has always been compile scope: e.g. https://github.com/kite-sdk/kite/blob/master/kite-data/kite-data-core/pom.xml#L126. The app parent pom should provide Avro anyway shouldn't it? (Like it does Crunch.)