message: fix Button lint errors
diff: import React from 'react'
  import {Button, ButtonPrimary, ButtonDanger, ButtonLink, ButtonOutline} from '..'
  -import theme from '../theme'
  import {render} from '../utils/testing'
  import {COMMON} from '../system-props'
  function noop() {}
  describe('Button', () => {
  - xit('is a system component', () => {
  + it('is a system component', () => {
  expect(Button.systemComponent).toEqual(true)
  })
  