Code of Conduct DRAFT

This pull request establishes a code of conduct that can be applied to multiple organizations. I urge all Hawaii tech meetup organizers and attendees to review this and provide feedback. Organizers, once this pull request is accepted, feel free to copy it to your organization's meetup group.

The establishment of a code of conduct in general should be non-controversial. Best case, things stay the same as they are now. Worst case, we have policies in place to head off future issues. To my knowledge, there have been no such issues at any tech events that I have attended (and I try to make it to most of them). @mikeal has an excellent writeup on codes of conduct at https://medium.com/node-js-javascript/codes-of-conduct-82ab2d88112d.

This closes #3.