Improve mbtiles grid.json rendering to be easier on API users.
Improve mbtiles grid.json rendering to be easier on API users.

nyurik/tilelive.js,tomhughes/tilelive.js,topwood/tilelive,paulovieira/tilelive,gravitystorm/tilelive.js,mapbox/tilelive,Norkart/tilelive.js,kyroskoh/tilelive,mapbox/tilelive.js