GitHub Issues Workflow for Chef

This RFC codifies the workflow of Chef maintainers while maintaining issues and contributions for Chef.

Special thanks to @btm / @lamont-granquist / @danielsdeleo / @mcquin / @adamedx / @jdmundrawala  who has helped put the first version come together.
This may be out of the scope of the RFC, but would anyone else benefit from the use of "Reviewed-By" tags in the commit message itself, much like the Linux kernel and other projects use?  It could make tracking down information about a given commit a bit easier, especially if the original author isn't a regular contributor to Chef.  It does raise the burden of reviewing a bit.