adds an animation to upvote/downvote
adds firework animations to upvote/downvote on imgur.
v0.11: forgot to remove some extraneous code.
v0.15: updated to support https. thanks imgur @roguedarkjedi for the suggestion
v0.20: enabled animation for comments as well
v0.25: fixed a bug where clicking on the edge of the vote button would trigger the animation even when "unclicking"
