Add badge

Cargo.toml

 [package]
-name = "ion"
-version = "0.1.0"
+name = "ion-shell"
+description = "The Ion Shell"
+repository = "https://github.com/redox-os/ion"
+version = "0.0.2"
+license-file = "LICENSE"
+readme = "README.md"
 authors = [
   "Jeremy Soller <jackpot51@gmail.com>",
   "Michael Gattozzi <mgattozzi@gmail.com>",

README.md

@@ -5,3 +5,5 @@ Redox, as well as the default shell.
 [![Build Status](https://travis-ci.org/redox-os/ion.svg)](https://travis-ci.org/redox-os/ion)
 [![MIT licensed](https://img.shields.io/badge/license-MIT-blue.svg)](./LICENSE)
 [![Coverage Status](https://coveralls.io/repos/redox-os/ion/badge.svg?branch=master&service=github)](https://coveralls.io/github/redox-os/ion?branch=master)
+[![crates.io](http://meritbadge.herokuapp.com/ion-shell)](https://crates.io/crates/ion-shell)
+