Add xmlhttprequest to devDependencies

Author: hdgarrood

package.json

@@ -7,6 +7,7 @@
     "gulp-plumber": "^1.0.0",
     "gulp-purescript": "^0.5.0",
     "express": "^4.13.1",
-    "body-parser": "^1.13.2"
+    "body-parser": "^1.13.2",
+    "xmlhttprequest": "^1.7.0"
   }
 }