Add geocoder handler for Mapzen

"Mapzen Search is a search engine for places worldwide, powered by open data. It turns addresses and place names into geographic coordinates, and turns geographic coordinates into places and addresses. With Mapzen Search, you’re able to turn your users’ place searches into actionable geodata and transform your geodata into real places."

Implementing a geocoder handler for MapZen Search API should be pretty straightforward. The API documentation can be found here.