Icon for FreeCol, fixes Issue #1305

Icon for **FreeCol**, Issue #1305.
Based on the new Icon for Unknown Horizons by @ChuckDaniels87 
![freecol](https://cloud.githubusercontent.com/assets/7050624/5086862/8f6f89c4-6f21-11e4-9fc5-aabf57286c2a.png)