Introduce Coding Standards Checks into Underscores

see
https://github.com/Automattic/_s/commit/f490e2839fb9cd8e6a92d283c6c45d3db5ca2398#diff-d41d8cd98f00b204e9800998ecf8427e
Merge pull request #40 from gatespace/_s-f490e28

Introduce Coding Standards Checks into Underscores