[npm] Upgrade ws to 0.7.2 and use stacktrace-parser that supports io.js

- ws 0.7 shipped with better io.js compatibility (see https://github.com/websockets/ws/releases for the changelog).
- stacktrace-parser used to list only Node 0.10 under its list of supported engines. This new version includes Node 1.x and 2.x (i.e. io.js) as well, which addresses the warning.

Test Plan: Run `npm install` under io.js -- no more warnings about a mismatched Node version.

Run the UIExplorer with the Chrome debugger. Can use it fine and no issues when reloading the app.

package.json

@@ -64,11 +64,11 @@
     "rebound": "^0.0.12",
     "sane": "^1.1.2",
     "source-map": "0.1.31",
-    "stacktrace-parser": "frantic/stacktrace-parser#493c5e5638",
+    "stacktrace-parser": "ide/stacktrace-parser#iojs",
     "uglify-js": "~2.4.16",
     "underscore": "1.7.0",
     "worker-farm": "^1.3.1",
-    "ws": "0.4.31",
+    "ws": "0.7.2",
     "yargs": "1.3.2"
   },
   "devDependencies": {