Replace wiki info icon #1457

Replaces a Wiki icon https://sourceforge.net/p/phpmyadmin/feature-requests/1457/?page=0


![old icon](https://f.cloud.github.com/assets/3743610/1230970/bee97b60-281e-11e3-9fd1-d001376ed8ba.PNG)
![new](https://f.cloud.github.com/assets/3743610/1230973/c6ceb8fe-281e-11e3-9aec-dc214f524cf2.PNG)