Updates CSSLint rule options

- box-model: This is because we are declaring `box-sizing: border-box`
  as a universal element. The rule cannot see this. So fails when it
  should be passing.

- regex-selectors: Are required in certain circumstances.
Fixes CSS Lint errors

> The property -moz-appearance is compatible with -webkit-appearance and
> should be included as well. Include all compatible vendor prefixes to
> reach a wider range of users. (compatible-vendor-prefixes)