log an error to console if the first element of the array passed to histogram is not a number.
add http prefix to source tags in index.html so it runs locally
change http -> https
Merge pull request #125 from tlatorre-uchicago/histogram-typeerror

Histogram TypeError
set args.y_axis_negative to false for log plots
added first barplot prototype for #126
added barplot prototype to wrong section
first pass at smoothers. Added ls, still need to debug lowess.
make the bounding boxes halfway between the previous point and the next point. this fixes issue #98.
Merge github.com:mozilla/metrics-graphics into log-axis