Rust0.11

**Cargo** integration!

If this PR is merged you can now build by
```
cargo build
```

and test by

```
cargo test
```

and if you need argparse in your project add a file called `Cargo.toml` to your project with the following content:
```
[package]

name = "sampleproject"
version = "0.1.0"
authors = ["john@doe.com"]

[dependencies.argparse]

branch = "rust0.11"
git = "https://github.com/tailhook/rust-argparse.git"
```

more about cargo at [crates.io](http://crates.io).