* hotfix/config-init-and-cli-flags:
  prepend slash to commits_url
  fix check_gh payload and secrets initialization
  don't try to load state from file on startup if doesn't exist
  print config after initialization

The `Context` toplevel should only store relatively static info that
applies globally, like the secrets.

When we accommodate multiple repos, a particular repo's config
should be moved out of the global toplevel context to the runtime
`State`, where it can coexist with other dynamic, repo-specific info
like pipeline status.

Repo state is namespaced by the full url of the repo, so that
so that identifiers are unique across platforms (github.com and
GH Enterprise).

For each test case, initializes a repo state from file if one exists.

The bindings should be usable by any file, not just state.atd

With repo-specific secrets, we'll need the repo name in order
to obtain the webhook token used for signature validation. So
parsing the request body for a GH payload needs to happen before,
not after, the signature check.

Define custom getters for retrieving GH secret values. As the
getter for each token type defaults to looking for a global value
if a repo-specific vaue isn't found, existing deployments don't
need to change.

We can now configure secrets, config, state, and incoming payload
separately, which lets us test multi-repo behavior more easily.

`push.multi_repo_custom_repo_secrets`
The correct repo-specific secrets configuration should be loaded
for the given payload repo.

`status.multi_repo_disallowed_repo`
If `allowed_repositories` excludes the payload repo, it should be
ignored.

`status.multi_repo_independent_status_state`
The status rules should be evaluated for the correct repo. In this
test case, it should correctly detect that `master`'s last build
status was a failure for the given payload repo, and issue a
success notification.