Losslessly compress images via Picabot

Hello! It is [**Picabot**, an automatic GitHub image optimizer](https://github.com/somu/picabot).

Your repository cointains some images, and I compressed them for you. Do not worry: the compression is lossless and based on [ImageOptim](http://imageoptim.com).

The reason why this bot exists: we need a faster web. There are people who have got a broadband, 4G and all the cool stuff. But still there are some countries where additional 50 kilobytes take a reasonable time to download (like couple of minutes). Plus, this PR is going to save some precious disk space, decrease server load, and so on. Still, if you do not need your images optimized, feel free to close this pull request.

Drop me a line: <somu@so.mu>, especially if you think the bot bugged this time. You also can donate so I could build a server which will send these precious pull requests more often. And also I could dedicate all my work time to open-source, and it is my dream, in fact. 

[![Donate](https://www.paypalobjects.com/en_US/i/btn/btn_donate_LG.gif)](https://www.paypal.com/cgi-bin/webscr?cmd=_s-xclick&hosted_button_id=ZXESQ83MM3H78)

Pull requests, forks and favs are welcome: https://github.com/somu/picabot