v3.0.0

• Removed Node 6 support
• Removed webpack 2 support
• cleanOnceBeforeBuildPatterns use emit hook instead of compile
• Do not clean files if webpack errors are present during initial build
• Replaced default export with named export CleanWebpackPlugin

// es modules
import { CleanWebpackPlugin } from 'clean-webpack-plugin';

// common js
const { CleanWebpackPlugin } = require('clean-webpack-plugin');