Fix settings view error. (Fix #13)

Hello guys!

I tried to use your app and it crashed when the settings window was being shown. This should fix it.
Therefore, I found another bug on the settings window that prevents another view from being shown. The only thing Xcode reported was `2014-04-09 15:40:21.107 LogCat[13018:303] NSViewAnimation target is not view or window ((null))`, and I couldn't find a way to fix it.