Update of our CoC to = CfA + our grievance policy

Feel free to re-add anything else from https://github.com/CodeForPortland/charter/blob/c820992cb45586d322aae933c25afbefcf58ee20/code_of_conduct.md
Formatting fixes
Link back to original CfA CoC
Merge pull request #5 from CodeForPortland/CFA-CoC

Update of our CoC to = CfA + our grievance policy