TEST: add travis ci test status image in README
-## arcus-memcached : Arcus Memory Cache Server
+## arcus-memcached : Arcus Memory Cache Server [![Build Status](https://travis-ci.org/naver/arcus-memcached.svg?branch=develop)](https://travis-ci.org/naver/arcus-memcached)
Arcus is a memcached-based cache cloud developed by NAVER Corp.
Memcached has been heavily modified to support functional and performance
