Prevent download of filter functions that are already in installation directory
Prevent download of filter functions that are already in installation directory

mnicholl/MOSFiT,guillochon/MOSFiT,bmockler/MOSFiT,guillochon/MOSFiT,villrv/MOSFiT,guillochon/FriendlyFit,villrv/MOSFiT,mnicholl/MOSFiT,bmockler/MOSFiT,mnicholl/MOSFiT,guillochon/MOSFiT