Add icon to add-ons such as Wunderlist.

[cyranodev]

Hey! I am so excited about this theme that I commit to donate some dollars, even though I live in Brazil and dollar exchange value here is rocketing up and up every day, if you commit to add more and more add-on icons to the package. :)

[lychichem]

Maybe a better way is to draw icon by yourself... You know that firefox have so many addons, the writer of this theme may not have enough time to make an icon for all the addons. And this means he has to try all the addons, that's impossible, I think.