Nodewebkit 910

Issues
1. websocket connects but does not transfer data.
2. npm and nodewebkit needs installed in configure.
3. develop mode will not open multiple windows.

fixes #910 

This is the only place `open_default_webbrowser` is used. Since we are moving to `node-webkit`, please drop `node/util.py::open_default_webbrowser` as well as any relevant tests from `test/test_util.py`.