message: [Improvement] update postcss config
diff: module.exports = {
  - plugins: [
  - require('postcss-easy-import')(),
  - require('precss')(),
  - require('postcss-calc')(),
  - require('autoprefixer')({
  + plugins: {
  + 'postcss-easy-import': {},
  + 'precss': {},
  + 'postcss-calc': {},
  + 'autoprefixer': {
  browsers: ['Android >= 4.0', 'iOS >= 7']
  - })
  - ]
  + }
  + }
  };
  