Add search type filter for Mapzen geocoder

server/extension/sql/20_geocode_street.sql

@@ -159,7 +159,7 @@ RETURNS Geometry AS $$
       country_iso3 = country_to_iso3(country)
     coordinates = geocoder.geocode(searchtext=searchtext, city=city,
                                    state_province=state_province,
-                                   country=country_iso3)
+                                   country=country_iso3, search_type='address')
     if coordinates:
       quota_service.increment_success_service_use()
       plan = plpy.prepare("SELECT ST_SetSRID(ST_MakePoint($1, $2), 4326); ", ["double precision", "double precision"])

server/lib/python/cartodb_services/cartodb_services/mapzen/geocoder.py

@@ -54,8 +54,9 @@ class MapzenGeocoder:
                                                 city,
                                                 state_province)
         request_params['text'] = search_string
-        request_params['layers'] = search_type if search_type else 'address'
         request_params['api_key'] = self._app_key
+        if search_type:
+            request_params['layers'] = search_type
         if country:
             request_params['boundary.country'] = country
         return request_params