Merge pull request #3 from nodejs/adds-contributing

Adds CONTRIBUTING.md (from iojs.org repo)

Author: therebelrobot

CONTRIBUTING.md

@@ -0,0 +1,53 @@
+## Developer's Certificate of Origin 1.0
+
+By making a contribution to this project, I certify that:
+
+* (a) The contribution was created in whole or in part by me and I
+  have the right to submit it under the open source license indicated
+  in the file; or
+* (b) The contribution is based upon previous work that, to the best
+  of my knowledge, is covered under an appropriate open source license
+  and I have the right under that license to submit that work with
+  modifications, whether created in whole or in part by me, under the
+  same open source license (unless I am permitted to submit under a
+  different license), as indicated in the file; or
+* (c) The contribution was provided directly to me by some other
+  person who certified (a), (b) or (c) and I have not modified it.
+
+
+## Code of Conduct
+
+This Code of Conduct is adapted from [Rust's wonderful
+CoC](https://github.com/rust-lang/rust/wiki/Note-development-policy#conduct).
+
+* We are committed to providing a friendly, safe and welcoming
+  environment for all, regardless of gender, sexual orientation,
+  disability, ethnicity, religion, or similar personal characteristic.
+* Please avoid using overtly sexual nicknames or other nicknames that
+  might detract from a friendly, safe and welcoming environment for
+  all.
+* Please be kind and courteous. There's no need to be mean or rude.
+* Respect that people have differences of opinion and that every
+  design or implementation choice carries a trade-off and numerous
+  costs. There is seldom a right answer.
+* Please keep unstructured critique to a minimum. If you have solid
+  ideas you want to experiment with, make a fork and see how it works.
+* We will exclude you from interaction if you insult, demean or harass
+  anyone.  That is not welcome behaviour. We interpret the term
+  "harassment" as including the definition in the [Citizen Code of
+  Conduct](http://citizencodeofconduct.org/); if you have any lack of
+  clarity about what might be included in that concept, please read
+  their definition. In particular, we don't tolerate behavior that
+  excludes people in socially marginalized groups.
+* Private harassment is also unacceptable. No matter who you are, if
+  you feel you have been or are being harassed or made uncomfortable
+  by a community member, please contact one of the channel ops or any
+  of the TC members immediately with a capture (log, photo, email) of
+  the harassment if possible.  Whether you're a regular contributor or
+  a newcomer, we care about making this community a safe place for you
+  and we've got your back.
+* Likewise any spamming, trolling, flaming, baiting or other
+  attention-stealing behaviour is not welcome.
+* Avoid the use of personal pronouns in code comments or
+  documentation. There is no need to address persons when explaining
+  code (e.g. "When the developer")