[cosmetic] add extra info to addon.xml 

added some extra field which we can use in future for our add-on browser.

i left website empty as i didn't know if i should put in http://www.cheezburger.com/
What i noticed throughout your add-ons is that the provider-name sometimes differs between each other. It would be nice if you could make them all the same en preferably use your forum user name.
This of course is no obligation and just a nice to have to make it easier for user to browse all your add-ons in one click.