add Travis-ci badge
[![Code Climate](https://codeclimate.com/github/yuru-yuri/Manga-Downloader/badges/gpa.svg)](https://codeclimate.com/github/yuru-yuri/Manga-Downloader)
[![Test Coverage](https://codeclimate.com/github/yuru-yuri/Manga-Downloader/badges/coverage.svg)](https://codeclimate.com/github/yuru-yuri/Manga-Downloader/coverage)
[![Issue Count](https://codeclimate.com/github/yuru-yuri/Manga-Downloader/badges/issue_count.svg)](https://codeclimate.com/github/yuru-yuri/Manga-Downloader)
+[![Travis CI result](https://travis-ci.org/yuru-yuri/Manga-Downloader.svg?branch=master)](https://travis-ci.org/yuru-yuri/Manga-Downloader.svg?branch=master)
+
[![GitHub issues](https://img.shields.io/github/issues/yuru-yuri/Manga-Downloader.svg)](https://github.com/yuru-yuri/Manga-Downloader/issues)
[![GitHub license](https://img.shields.io/badge/license-MIT-blue.svg)](https://raw.githubusercontent.com/yuru-yuri/Manga-Downloader/master/LICENSE)
[![GitHub stars](https://img.shields.io/github/stars/yuru-yuri/Manga-Downloader.svg)](https://github.com/yuru-yuri/Manga-Downloader/stargazers)
