Revert "cal-heatmap updated to version 3.3.8"

This reverts commit 7f06f112df28bd470927cdc62846b3f8c6457677.
Revert "Revert "cal-heatmap updated to version 3.3.8""

This reverts commit 75a26e13203b262da8515263c97cfe5091a9c770.
Revert "Changed README to reflect correct d3 version"

This reverts commit 8f9701dc41aa693cef3d94ebe7cd2ef78f487dfb.