Force native window

- Force native frame and suppress the Chromium default blue frame. This
resolves issues with Windows systems that are running in VM's and cannot
enable Aero Glass. Atom-Shell was adding the default Chromium blue frame
even when frame was set to false in the BrowserWindow options.
Fix merge conflict with native_window_views.cc
Fix CPP formatting
Merge pull request #815 from frankhale/force-native-window

Force native window