Before this change, the authorize hook was invoked twice: once before
authentication and again after (if settings.requireAuthorization is
true). Now pre-authentication authorization is instead handled by a
new preAuthorize hook, and the authorize hook is only invoked after
the user has authenticated.
Rationale: Without this change it is too easy to write an
authorization plugin that is too permissive. Specifically:
* If the plugin does not check the path for /admin then a non-admin
user might be able to access /admin pages.
* If the plugin assumes that the user has already been authenticated
by the time the authorize function is called then unauthenticated
users might be able to gain access to restricted resources.
This change also avoids calling the plugin's authorize function twice
per access, which makes it easier for plugin authors to write an
authorization plugin that is easy to understand.
This change may break existing authorization plugins: After this
change, the authorize hook will no longer be able to authorize
non-admin access to /admin pages. This is intentional. Access to admin
pages should instead be controlled via the `is_admin` user setting,
which can be set in the config file or by an authentication plugin.
Also:
* Add tests for the authenticate and authorize hooks.
* Disable the authentication failure delay when testing.
This makes it possible for reverse proxies to transform 403 errors
into something like "upgrade to a premium account to access this
pad".
Also add some webaccess tests.
