Add description of how to run the tests to README.md
Add description of how to run the tests to README.md

Fixes #42

emilio/rust-bindgen,jdub/rust-bindgen,rust-lang/rust-bindgen,rust-lang/rust-bindgen,catdesk/rust-bindgen,jdub/rust-bindgen,rust-lang/rust-bindgen,rust-lang/rust-bindgen,catdesk/rust-bindgen,jdub/rust-bindgen,catdesk/rust-bindgen,emilio/rust-bindgen,emilio/rust-bindgen,emilio/rust-bindgen,jdub/rust-bindgen,catdesk/rust-bindgen,emilio/rust-bindgen