Added support to download images from multiple regions.

[freaksterrao]

1. If downloading from multiple regions, the code now does not force the wallpaper. Instead it is expected that user sets the wallpaper to be a slide show pointing to Bing Wallpaper\Year folder
2. Added support for hiding the console window. I use it when I run it as a schedule task.
3. This code does not have the change that sets the proxy since .NET automatically uses the system proxy by default in my testing
4. Fixed improper disposing of WebClients that caused a TimeoutException when downloading multiple images.

[josueespinosa]

Hi @freaksterrao, sorry for the delayed response, I was on a business trip in Mexico. Everything looks great, but I need you to fix these things first:

1. Build errors (the type or namespace name "market" could not be found)
2. Remove gratuitous whitespace
3. Follow One True Brace indent style

I've been meaning to push something like what you added for a while. The next step for me will probably be to create a GUI for the settings management and perhaps browsing the past 30 days of wallpapers available. Thanks for your help!