Enable ESLint's prefer-* rules to match the current style

[XhmikosR]

no-var etc so that we match the current style but keeping Node.js 8.6 compatibility.

Personally, I'd just go with xo instead of reinventing the wheel, but it's the maintainers' call :)

[jonschlinkert]

@XhmikosR sorry for the late reply, can you give me a little more detail about the prefer-* rules you have in mind (assuming you remember at this point). I'm very interested in adding more rules that match the current style, but would prefer to stick with just eslint for now.

[XhmikosR]

@jonschlinkert I will try to have a look in the next days; I surely don't remember the rules right now :P