Replace sprintf dependency with built-in or sprintf-js

[HamletDRC]

The owner of sprintf (https://github.com/maritz/node-sprintf) says that node-sprintf is no longer maintained. He suggests replacing your sprintf with either the built-in Javascript methods or use the sprintf-js package.

My issue with Whiskey's usage of sprintf is that its package.json file does not contain a license declaration. This is a problem for my legal department. I asked the maintainer to update the file as a separate issue, but it is unclear if he'll do it. He recommended that I create an issue with Whiskey asking the project to remove the dependency. Discussion here: maritz/node-sprintf#18