Allow running within node-webkit

[UhhhWaitWhat]

Node webkit gives our module access to a window object, even though we still run in a node environment. Therefore we should check, if we can access process and not if we can access window.

(I hope, I did this right, first pull-request I have ever opened)

[davidchambers]

This change looks fine, though you should run make and commit the changes to the JavaScript files.

[UhhhWaitWhat]

ok, will do, should I squash into the old commit or should i add a new one?

[davidchambers]

Squash, please. :)

[UhhhWaitWhat]

Done

[davidchambers]

Thanks.