Support using a common redis connection

If sentinel_host or sentinel_cluster_id is not provided it will try to
connect with a redis_host parameter

server/extension/sql/0.5.0/99_geocoder_server_user.sql

@@ -0,0 +1,15 @@
+DO $$
+BEGIN
+    IF NOT EXISTS (
+        SELECT *
+        FROM   pg_catalog.pg_user
+        WHERE  usename = 'geocoder_api') THEN
+
+            CREATE USER geocoder_api;
+    END IF;
+    GRANT EXECUTE ON ALL FUNCTIONS IN SCHEMA cdb_dataservices_server TO geocoder_api;
+    GRANT EXECUTE ON ALL FUNCTIONS IN SCHEMA public TO geocoder_api;
+    GRANT USAGE ON SCHEMA cdb_dataservices_server TO geocoder_api;
+    GRANT USAGE ON SCHEMA public TO geocoder_api;
+    GRANT SELECT ON ALL TABLES IN SCHEMA public TO geocoder_api;
+END$$;