Merge pull request #39 from php-http/license

Adding license badge

Author: dbu

README.md

@@ -1,7 +1,8 @@
 # PSR-7 Multipart Stream Builder
 
 [![Latest Version](https://img.shields.io/github/release/php-http/multipart-stream-builder.svg?style=flat-square)](https://github.com/php-http/multipart-stream-builder/releases)
-[![Build Status](https://img.shields.io/travis/php-http/multipart-stream-builder.svg?style=flat-square)](https://travis-ci.org/php-http/multipart-stream-builder)
+[![Software License](https://img.shields.io/badge/license-MIT-brightgreen.svg?style=flat-square)](LICENSE)
+[![Build Status](https://img.shields.io/travis/php-http/multipart-stream-builder/master.svg?style=flat-square)](https://travis-ci.org/php-http/multipart-stream-builder)
 [![Code Coverage](https://img.shields.io/scrutinizer/coverage/g/php-http/multipart-stream-builder.svg?style=flat-square)](https://scrutinizer-ci.com/g/php-http/multipart-stream-builder)
 [![Quality Score](https://img.shields.io/scrutinizer/g/php-http/multipart-stream-builder.svg?style=flat-square)](https://scrutinizer-ci.com/g/php-http/multipart-stream-builder)
 [![Total Downloads](https://img.shields.io/packagist/dt/php-http/multipart-stream-builder.svg?style=flat-square)](https://packagist.org/packages/php-http/multipart-stream-builder)