Cargo dependency tree

Node's `npm` has a nice feature: You can list all packages and their dependencies. `cargo` has no such feature included, but `cargo-tree` delivers. Install it with

cargo install cargo-tree

and it gives you a nice tree of dependencies for all libraries in `Cargo.toml`:

$ cargo tree
postgres v0.10.2 (file:///Volumes/git/rust/rust-postgres)
├── bufstream v0.1.1
├── byteorder v0.4.2
├── hex v0.1.0
├── log v0.3.4
│   └── libc v0.2.4
├── net2 v0.2.20
│   ├── cfg-if v0.1.0
│   ├── kernel32-sys v0.2.1
│   │   └── winapi v0.2.5
│   ├── libc v0.2.4 (*)
│   ├── winapi v0.2.5 (*)
│   └── ws2_32-sys v0.2.1
│       └── winapi v0.2.5 (*)
└── phf v0.7.9
    └── phf_shared v0.7.9