use master api key in setDBAuth

lib/cartodb/backends/pg_connection.js

@@ -21,35 +21,17 @@ module.exports = PgConnection;
 // @param callback function(err)
 //
 PgConnection.prototype.setDBAuth = function(username, params, callback) {
-    var auth_user = global.environment.postgres_auth_user;
-    var auth_pass = global.environment.postgres_auth_pass;
-
-    this.metadataBackend.getUserId(username, (err, userId) => {
+    this.metadataBackend.getMasterApikey(username, (err, apikey)=> {
         if (err) {
             return callback(err);
         }
-        
-        const userParams = {
-            user_id: userId
-        };
 
-        params.dbuser = _.template(auth_user, userParams);
+        params.dbuser = apikey.databaseRole;
+        params.dbpassword = apikey.databasePassword;
 
-        if (!auth_pass || !auth_pass.match(/\buser_password\b/)) {
-            return callback();
-        }
-
-        this.metadataBackend.getUserDBPass(username, (err, userPassword) => {
-            if (err) {
-                return callback(err);
-            }
-
-            userParams.user_password = userPassword;
-            params.dbpassword = _.template(auth_pass, userParams);
-
-            callback();
-        });
+        callback();
     });
+
 };
 
 // Set db connection parameters to those for the given username