Fix typo. Refs #82.
Use only most significant term in index. Cluster phrases by sig term.
Fix phrase clustering for shardlevel <= 3.
Update S3 fixtures.
Merge pull request #84 from mapbox/dev-phrase-cluster

Dev phrase cluster
Use tilelive to support more protocols. Refactor autoloading.
Loader fixes.
Merge branch 'dev' into address
Adapt to GeoJSON input.