fix badge

README.md

@@ -3,8 +3,8 @@
 [![Travis Build Status](https://travis-ci.org/Covertness/coap-rs.svg?branch=master)](https://travis-ci.org/Covertness/coap-rs)
 [![Windows Build Status](https://ci.appveyor.com/api/projects/status/ic36jdu4xy6doc59?svg=true)](https://ci.appveyor.com/project/Covertness/coap-rs)
 ![Downloads](https://img.shields.io/crates/d/coap.svg?style=flat)
-[![crates.io](http://meritbadge.herokuapp.com/coap)](https://crates.io/crates/coap)
-[![Coverage Status](https://coveralls.io/repos/Covertness/coap-rs/badge.svg?branch=master&service=github)](https://coveralls.io/github/Covertness/coap-rs?branch=master)
+[![](https://meritbadge.herokuapp.com/coap)](https://crates.io/crates/coap)
+[![Coverage Status](https://coveralls.io/repos/github/Covertness/coap-rs/badge.svg?branch=master)](https://coveralls.io/github/Covertness/coap-rs?branch=master)
 [![MIT licensed](https://img.shields.io/badge/license-MIT-blue.svg)](./LICENSE)
 
 A fast and stable [Constrained Application Protocol(CoAP)](https://tools.ietf.org/html/rfc7252) library implemented in Rust.