(#362) Part 3: implement querying against simple keywords. r=nalexander
(#362) Part 3: implement querying against simple keywords. r=nalexander

ncalexan/mentat,mozilla/mentat,mozilla/mentat,mozilla/mentat,ncalexan/datomish,mozilla/mentat,ncalexan/datomish,ncalexan/mentat,mozilla/mentat,ncalexan/mentat,ncalexan/mentat,mozilla/mentat,ncalexan/mentat,ncalexan/mentat