Add version & travis badges

Author: lneveu

README.md

@@ -1,5 +1,8 @@
 # cssnano-webpack-plugin
 
+![npm](https://img.shields.io/npm/v/cssnano-webpack-plugin)
+[![Build Status](https://travis-ci.org/lneveu/cssnano-webpack-plugin.svg?branch=master)](https://travis-ci.org/lneveu/cssnano-webpack-plugin)
+
 This plugin uses [cssnano](https://cssnano.co) to optimize and minify your CSS.
 
 Fully integrated in Webpack ecosystem: based on compiler hooks, respecting default Webpack output sources and compatible with other plugins like *SourceMapDevToolPlugin* or *webpack-subresource-integrity*.