OS-agnostic browser start.

### Motivation:
* [os.uname](https://docs.python.org/2/library/os.html#os.uname) is only available in 'recent flavors of Unix', and won't work on Windows.

### Changelog:
* Use python's [webbrowser](https://docs.python.org/2/library/webbrowser.html) to open the browser.