Relicense clippy

Documentation on relicensing in previous commit

Fixes #2885

Also fixes #3093, fixes #3094, fixes 3095, fixes #3096, fixes #3097, fixes #3098,
fixes #3099, fixes #3100, fixes #3230

Author: Manishearth

Cargo.toml

@@ -11,7 +11,7 @@ authors = [
 description = "A bunch of helpful lints to avoid common pitfalls in Rust"
 repository = "https://github.com/rust-lang-nursery/rust-clippy"
 readme = "README.md"
-license = "MPL-2.0"
+license = "MIT/Apache-2.0"
 keywords = ["clippy", "lint", "plugin"]
 categories = ["development-tools", "development-tools::cargo-plugins"]
 build = "build.rs"