Changelog:
Node
* node-webkit's version is added to process.versions

Core
* Support getUserMedia API
* Implement file select dialog
* Add `nwdirectory` and `nwsaveas` attribute for <input type='file'>
* Add new nw protocol, having nw:blank and nw:version now
* Context created by window.open has node's symbols now
* All DOM operations don't need to be user gesture now
* Add window.title for manifest file

Windows
* Fix crash when using devtools on some machines

Mac & Linux
* Fix issues with node native modules

Windows & Linux
* Implement file download dialogs