Getting the plugin started (NAWQAAN-361)

I think this works because it is using type-coercive equality. It is passing multiple tests where 0 is being passed in as margin: https://github.com/USGS-CIDA/jquery.flot.custom-canvas-legend/pull/1/files#diff-0d26faeecb6e44e7c4b8e2937e5c8e3bR61