add back in dropped @required_scipy decorator
add back in dropped @required_scipy decorator

jhamman/xarray,shoyer/xarray,rabernat/xray,jhamman/xarray,markelg/xray,shoyer/xarray,jhamman/xray,markelg/xray,markelg/xray,shoyer/xray,pydata/xarray,xray/xray,rabernat/xray,pydata/xarray,jhamman/xarray,jcmgray/xarray,chunweiyuan/xarray,pydata/xarray