Add bookmarklet option to support all browsers

To run the bookmarklet in dev mode:
- `grunt bookmarklet_server`
- create a bookmark:

```javascript

javascript: (function() { var s = document.createElement('script'); s.src = 'http://localhost:9191/load_inspector.js'; document.body.appendChild(s); }());

````

Clicking on the bookmark opens a new window with the inspector.  Make
sure to unblock the popup.

This can also be used to debug the inspector (in the popup) using the inspector
extension.
Close inspector when inspected window unloads
Prefix flexbox with -webkit for safari
Add URLS to window.postMessage for security
Upload dist_bookmarklet to s3
Merge pull request #190 from emberjs/bookmark

Add bookmarklet option to support all browsers