First commit of the matchmaker APIs

This is a wip translation of the matchmaker APIs into avro.

Autogenerated docs are here: http://cassiedoll.github.io/matchmaker-staging.html
I'm not quite sure why REF and ALT are needed to describe a "Gene". I mean, shouldn't genes always be "REF" by definition? May be I'm misunderstanding the purpose of this "GAGene" record....