Add forkit.gif

From https://github.com/knotdvn/fork-spoon
Used in index.html

The file was missing, resulting in an ugly _can't load that file_ icon.
![image](https://cloud.githubusercontent.com/assets/10091584/5374008/80433c3c-806c-11e4-831d-67a3898d4e14.png)

After the change everithing looks right.