SCHEMA-659. Avro parser handle name-spaces properly

 - Properly define and implement name-spaces:
   - The following are absolute Avro names: ".SimpleName", "ns.SimpleName" and ".ns.SimpleName"
   - The name "SimpleName" is resolved against a current default name-space.

issue: https://jira.kiji.org/browse/SCHEMA-659
review: https://review.kiji.org/r/1651