Add support for Repository Topics

[dan2k3k4]

It would be cool to add, remove, and list topics for repositories.

https://developer.github.com/v3/previews/#repository-topics

However it's currently in preview mode so requires HTTP Header to be: Accept: application/vnd.github.mercy-preview+json

See note at top of: https://developer.github.com/v3/repos/

[BigBlueHat]

Looks like this is possible now via --label: https://github.com/node-gh/gh#repo-create-label

[BigBlueHat]

It would be nice to see labels in the details, however. 😃

[BigBlueHat]

Ignore me. Topics != labels... Sorry for the noise, but having these show in repository details would also be wonderful. Thanks!

[protoEvangelion]

Thanks for chiming in @BigBlueHat so are you saying topics would be nice to see or labels?