Add npm badge [ci skip]

Author: kristerkari

README.md

@@ -1,5 +1,6 @@
 # React Native CSS Media Query processor
 
+[![NPM version](http://img.shields.io/npm/v/react-native-css-media-query-processor.svg)](https://www.npmjs.org/package/react-native-css-media-query-processor)
 [![Build Status](https://travis-ci.org/kristerkari/react-native-css-media-query-processor.svg?branch=master)](https://travis-ci.org/kristerkari/react-native-css-media-query-processor)
 [![Build status](https://ci.appveyor.com/api/projects/status/1itowtpn7a51rc5x/branch/master?svg=true)](https://ci.appveyor.com/project/kristerkari/react-native-css-media-query-processor/branch/master)
 [![PRs Welcome](https://img.shields.io/badge/PRs-welcome-brightgreen.svg)](https://egghead.io/courses/how-to-contribute-to-an-open-source-project-on-github)