Add Coding Standard

[tunnckoCore]

Apply all across repos feross/standard, or if you want more customizable and semicolons sindresorhus/xo ?

[tunnckoCore]

or semistandard ? @jstransformers/owners it seems most of the repos follows mostly semistandard so we can use it?

[RobLoach]

http://npm.im/semistandard

I'm a fan, likely something we could bring directly into test-jstransformer so we don't need to define it in Boilerplate.

[RobLoach]

http://npm.im/xo