Add build status badge

Author: baopham

README.md

@@ -4,6 +4,7 @@ laravel-dynamodb
 [![Latest Stable Version](https://poser.pugx.org/baopham/dynamodb/v/stable)](https://packagist.org/packages/baopham/dynamodb)
 [![Total Downloads](https://poser.pugx.org/baopham/dynamodb/downloads)](https://packagist.org/packages/baopham/dynamodb)
 [![Latest Unstable Version](https://poser.pugx.org/baopham/dynamodb/v/unstable)](https://packagist.org/packages/baopham/dynamodb)
+[![Build Status](https://travis-ci.org/baopham/laravel-dynamodb.svg?branch=master)](https://travis-ci.org/baopham/laravel-dynamodb)
 [![License](https://poser.pugx.org/baopham/dynamodb/license)](https://packagist.org/packages/baopham/dynamodb)
 
 Supports all key types - primary hash key and composite keys.