Relicense as Apache 2.0

[ewdurbin]

A recent revelation that significant portions of this code base had been quietly copied into https://github.com/pinterest/pymemcache via https://github.com/pinterest/pymemcache/commit/cff5abfad59baa593996fe7e240fd3944e2c4af2 has lead me to make a decision to relicense this project under Apache 2.0, adding a NOTICE file per clause 4(d) of the Apache 2.0 license.

This issue will serve as a formal request to @sontek and @chriso for permission to do so, in light of their contributions.

@sontek and @chriso, please reply with either a confirmation or any objections.

[chriso]

:star:

[sontek]

:+1:

[ewdurbin]

Thank you both for quick replies.