v1.2.0

• Improve performance of GeoJSON and TopoJSON format generation by using ujson (See #139)
• Improve performance of MVT format generation by using builtin round function (See #144)
• Reduce database pressure by use psycopg2 connection pools (See #141)
• Reduce database requests by registering hstore/json (See #142)
• Reduce memory usage during tile seeding (See #126)
• Expose unique option for seeding tile generator (See #127)
• Support long zooms (See #130)