Add cdb_mapzen_isochrone to client

On behalf of @iriberri.

client/renderer/interface.yaml

@@ -103,6 +103,16 @@
     - { name: range, type: "integer[]" }
     - { name: options, type: "text[]", default: 'ARRAY[]::text[]' }
 
+- name: cdb_mapzen_isochrone
+  return_type: SETOF cdb_dataservices_client.isoline
+  multi_row: true
+  multi_field: true
+  params:
+    - { name: source,  type: "geometry(Geometry, 4326)" }
+    - { name: mode, type: text }
+    - { name: range, type: "integer[]" }
+    - { name: options, type: "text[]", default: 'ARRAY[]::text[]' }
+
 - name: cdb_route_point_to_point
   return_type: cdb_dataservices_client.simple_route
   multi_field: true