Update min/max calculations in slopegraph template. Closes #153.
Update min/max calculations in slopegraph template. Closes #153.

nprapps/dailygraphics,stlpublicradio/dailygraphics,stlpublicradio/dailygraphics,nprapps/dailygraphics,nprapps/dailygraphics,stlpublicradio/dailygraphics,nprapps/dailygraphics,stlpublicradio/dailygraphics