Allow editing hosting policies via command line

Summary:
Exposes the serve-over-http and serve-over-ssh options for a repository
to the bin/repository edit endpoint.

Test Plan: Ran bin/repository with the new options over several hundred repos

Reviewers: epriestley, #blessed_reviewers

Reviewed By: epriestley, #blessed_reviewers

Subscribers: Korvin, chasemp, 20after4, epriestley

Differential Revision: https://secure.phabricator.com/D14250