Relicense Tokio exclusively under the MIT license. (#215)

This patch relicenses the Tokio project exclusively under the MIT
license. Before this, the project was dual licensed under MIT and Apache
2. As such, switching to only MIT is permitted.

Fixes #202

tokio-threadpool/Cargo.toml

@@ -4,7 +4,7 @@ version = "0.1.0"
 documentation = "https://docs.rs/tokio-threadpool"
 repository = "https://github.com/tokio-rs/tokio"
 homepage = "https://github.com/tokio-rs/tokio"
-license = "MIT/Apache-2.0"
+license = "MIT"
 authors = ["Carl Lerche <[email protected]>"]
 description = """
 A task scheduler backed by a work-stealing thread pool.

tokio-threadpool/README.md

@@ -45,17 +45,10 @@ pub fn main() {
 
 ## License
 
-This project is licensed under either of
-
- * Apache License, Version 2.0, ([LICENSE-APACHE](../LICENSE-APACHE) or
-   http://www.apache.org/licenses/LICENSE-2.0)
- * MIT license ([LICENSE-MIT](../LICENSE-MIT) or
-   http://opensource.org/licenses/MIT)
-
-at your option.
+This project is licensed under the [MIT license](../LICENSE).
 
 ### Contribution
 
 Unless you explicitly state otherwise, any contribution intentionally submitted
-for inclusion in Tokio by you, as defined in the Apache-2.0 license, shall be
-dual licensed as above, without any additional terms or conditions.
+for inclusion in Tokio by you, shall be licensed as MIT, without any additional
+terms or conditions.