Gitaly itself hold very little state, other than the data on disk. This
limits the interfaces to set feature flags. Gitaly now has the ability
to interpret the request metadata to check for feature flags.
https://gitlab.com/gitlab-org/gitaly/merge_requests/704
This allows clients control on the Gitaly server, and given that Rails
has an internal chatops interface to set these values this was chosen as
solution.

Known limitation right now, is that this package doesn't support the opt
out that other Gitaly features do.