[8/7] Relicense under dual MIT / Apache v2

[Manishearth]

This is one of the sub-issues for relicensing this repo to MIT / Apache v2, the license used by most of the Rust ecosystem. For more information, see #3093

To agree to relicensing, comment with :

I license past and future contributions under the dual MIT/Apache-2.0 license, allowing licensees to chose either at their option.

This issue is for folks who made pull requests after #3093 was opened.

See #3093 (comment)

[Manishearth]

@JayKickliter accepted in #3195

[JoshMcguigan]

I license past and future contributions under the dual MIT/Apache-2.0 license, allowing licensees to chose either at their option.

[PSeitz]

I license past and future contributions under the dual MIT/Apache-2.0 license, allowing licensees to chose either at their option.

[vi]

I license my past and future contributions to this project under the dual MIT/Apache-2.0 license, allowing licensees to chose either at their option.

[mbrubeck]

I license past and future contributions under the dual MIT/Apache-2.0 license, allowing licensees to chose either at their option.

[chaoticlonghair]

I license my past and future contributions to this project under the dual MIT/Apache-2.0 license, allowing licensees to chose either at their option.

[daubaris]

I license past and future contributions under the dual MIT/Apache-2.0 license, allowing licensees to chose either at their option.