adopt Developer Certificate of Origin

background: http://lwn.net/Articles/592503/

> There are three important components to any contributor agreement: an assertion that the contributor has the right to contribute the code, a statement of actual contribution, and consent that the code may be distributed under the project's licenses.
>
> Every project should be able to prove that every line of code it distributes was intentionally contributed... A project can't just pick up patches off the street and hope that all will be well; if the code was not overtly contributed, the author could always try to revoke the project's right to the code, leading to trouble.
>
> Equity is one of the fundamental principles of the free software community; it is important that everybody meets on an equal basis. But, when company lawyers sit down to write a contributor agreement, they will naturally write that agreement to favor their employers; that is just part of what lawyers do. **The result is inequity, and that destroys communities.**

(emphasis mine)

http://developercertificate.org/