Merge pull request #162 from h-michael/gitter-link

Add gitter badge

Author: tomhoule

README.md

@@ -3,6 +3,7 @@
 [![Build Status](https://travis-ci.org/graphql-rust/graphql-client.svg?branch=master)](https://travis-ci.org/graphql-rust/graphql-client)
 [![docs](https://docs.rs/graphql_client/badge.svg)](https://docs.rs/graphql_client/latest/graphql_client/)
 [![crates.io](https://img.shields.io/crates/v/graphql_client.svg)](https://crates.io/crates/graphql_client)
+[![Join the chat](https://badges.gitter.im/Join%20Chat.svg)](https://gitter.im/juniper-graphql/graphql-client)
 
 A typed GraphQL client library for Rust.