Merge pull request #690 from jakubadamw/master

Add `sfackler/cargo-tree`

README.md

@@ -389,6 +389,7 @@ See also [A comparison of operating systems written in Rust](https://github.com/
   * [cargo-release](https://crates.io/crates/cargo-release) — tool for releasing git-managed cargo project, build, tag, publish, doc and push [<img src="https://api.travis-ci.org/sunng87/cargo-release.svg?branch=master">](https://travis-ci.org/sunng87/cargo-release)
   * [cargo-script](https://crates.io/crates/cargo-script) — lets people quickly and easily run Rust "scripts" which can make use of Cargo's package ecosystem [<img src="https://api.travis-ci.org/DanielKeep/cargo-script.svg?branch=master">](https://travis-ci.org/DanielKeep/cargo-script)
   * [cargo-testify](https://crates.io/crates/cargo-testify) — watches files changes, runs tests and notifies about the result with friendly OS notification [<img src="https://api.travis-ci.org/greyblake/cargo-testify.svg?branch=master">](https://travis-ci.org/greyblake/cargo-testify)
+  * [cargo-tree](https://github.com/sfackler/cargo-tree) – Cargo subcommand that visualizes a crate's dependency graph in a tree-like format [![CircleCI](https://circleci.com/gh/sfackler/cargo-tree.svg?style=shield)](https://circleci.com/gh/sfackler/cargo-tree)
   * [cargo-update](https://crates.io/crates/cargo-update) — cargo subcommand for checking and applying updates to installed executables [<img src="https://api.travis-ci.org/nabijaczleweli/cargo-update.svg?branch=master">](https://travis-ci.org/nabijaczleweli/cargo-update)
   * [cargo-watch](https://crates.io/crates/cargo-watch) — utility for cargo to compile projects when sources change [<img src="https://api.travis-ci.org/passcod/cargo-watch.svg?branch=master">](https://travis-ci.org/passcod/cargo-watch)
   * [liuchong/cargo-x](https://github.com/liuchong/cargo-x) — A very simple third-party cargo subcommand to execute a custom command [<img src="https://api.travis-ci.org/liuchong/cargo-x.svg?branch=master">](https://travis-ci.org/liuchong/cargo-x)