Polished the SMF favicon. 

Centered fulcrum and added a 2px border radius. Just a small tweak to make it look a tad better.

Signed-off-by: Draven Xarcell Vestatt <draven.vestatt@xarpixels.com>

Here is a screenshot of a new versus old comparison.
![screenshot_smf-favicon-new-vs-old](https://f.cloud.github.com/assets/6114450/2092016/ce9e61bc-8ea6-11e3-95e7-a9739eb1303f.jpg)