build: add prettier #93

[ianmcburnie]

Three commits:

1. Updates devDeps, this one is significant because it looks like the browser list config bumped Safari to 12 which has support for let & const. So we see those js dist files being updated appropriately.
2. Adds the prettier dependencies and config. I decided to drop the eslint --fix portion and just let prettier handle all formatting from now on
3. After running prettier on all files. Most of the noise is single quotes to double quotes and 4 spaces to 2. To keep noise down I also added a printWidth: 120. I may remove that later, but to be honest I like it at that setting.

[LuLaValva]

Looks good!