Use fixed version for engine.io in package.json

package.json

@@ -17,8 +17,8 @@
         "debug": "~0.7.4",
         "ejs": "~0.8.3",
         "emmet": "git://github.com/cloud9ide/emmet-core.git#2ff6dc06ad",
-        "engine.io": "~1.5.1",
-        "engine.io-client": "~1.5.1",
+        "engine.io": "1.5.3",
+        "engine.io-client": "1.5.3",
         "eslint": "git://github.com/cloud9ide/eslint.git#dc500e81162bf0cb4747a4a415c121b0c46975cb",
         "http-error": "~0.0.5",
         "less": "^2.4.0",