update javascript to show subButton and toggle .sub

Jenae, you had a good start with your javscript, but the syntax was a little messy. I left some comments in the code, as well as made comments in Github, [which you can see here](https://github.com/benkutil/micagraphicdesign.org/commit/f443990d626b39aca319fc88ebb70692a713168c#comments).