Initial release based on Protobuf

Alpha pre-release supporting major feature update. This release is not
backwards compatible with previous releases due to several changes to
the schemas that were required to move to protocol buffers.

• This release includes the code changes necessary for the migration
  to protocol buffers from Avro.
• Client applications will need to be rebuilt to the new schemas and
  use the protobuf json serialization libraries to be compatible
  with this version of the server.