Heatmap cannot display CSV without weight

[kaikuchn]

Hi,

thank you for providing this neat heatmap, especially for hosting a live demo. I was able to work out how to use your app even though it initially failed to load my csv. When a CSV has no weights column you push data points this way when the CSV does have a weight column, however, you push data points that way.

Since in the former case you do not push an object with a location key, displaying the heatmap fails.