Temporarily use master branch docker images for API

support for the libpostal service has not yet been merged to production,
so we need this for now. It should be removed once libpostal support is
stable

docker-compose.yml

@@ -23,7 +23,7 @@ services:
       - "./pelias.json:/code/pelias.json"
   api:
     depends_on: [ "baseimage" ]
-    image: pelias/api
+    image: pelias/api:master
     container_name: pelias_api
     restart: always
     environment: [ "PORT=4000" ]