MXS-1220: Add PUT support for /maxscale/ resource

The /maxscale/ resource now supports PUT requests which modify core
parameters. As not all parameters can be changed at runtime, only
modifications to parameters that support runtime configuration are
allowed.

server/core/test/rest-api/test/users.js

@@ -4,7 +4,7 @@ require("../utils.js")()
 describe("Users", function() {
     before(startMaxScale)
 
-    user = {
+    var user = {
         data: {
             id: "user1",
             type: "inet",