Added bower.json file for bower registration, resolves #11.

Hey, for registration on bower: http://bower.io/docs/creating-packages/#register, and resolving issue https://github.com/ttsvetko/HTML5-Desktop-Notifications/issues/11, if you like. 

So that this can be installed using 'bower install HTML5-Desktop-Notifications'. May require changes in the package name. 

Thanks for creating this library!