Added apt-get update to travis
Added apt-get update to travis

arjanfrans/plane,ArjanFrans/brecourt,ArjanFrans/brecourt,arjanfrans/plane,arjanfrans/plane2d,ArjanFrans/brecourt,arjanfrans/plane2d,arjanfrans/plane2d,arjanfrans/plane,arjanfrans/plane,ArjanFrans/brecourt,arjanfrans/plane2d