Add missing guidelines from mavenlink welcome repo

Mavenlink welcome now references this repo, but there were a few missing items

- avoid using semicolons
- don't use braces when defining an object
- use a template instead of putting html in coffeescript
- minimize usage of fat arrow

see also: https://github.com/mavenlink/welcome/commit/3ede9050002170a4d9859844ffeb525ace1fb0e5