More lenient validation of north and south bbox values.
More lenient validation of north and south bbox values.

This now matches the validation in mbtiles.

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