Major update to settings window.

Now using datacontext and binding.
UI got minor updates.
Merged master into Dropbox support by jh
Changed layout in settings window
Minor code changes
Cleanup and refactoring

Removed MainWindow and moved code to App
Removed SingleInstance class and support for now
Removed share.ico in content folder
Changed hotkey class for better support
Minor cleanup and adjustment
Remember to unregister windows when closed
Show balloontop instead of message box
Bring windows to front when trying to open second instance
Cleanup and stuff
Fixed active provider not being saved if required web auth
Resharper pleasing
Fixed naming causing app not to build
Moved blocking code to background worker (Dropbox auth)