Add redirectUrl() to allow redirects that don’t force a call through Url().
Add support for controllers in plugins.

- Autoload controllers with all autoloader maps.
- When finding a controller check to see if it
  belongs to a plugin or application.
Merge branch 'feature/plugincontrollers' into feature/multisite
Remove Gdn_Controller->ControllerFolder.

The ControllerFolder is a really old artifact of pre 2.0 Vanilla. It was intended to allow for controllers nested into folders which ended up never being used.
Don’t dispatch to controllers that aren’t in a /controllers folder.
Set the Gdn_Controller->Application to the name of the plugin if
dispatching to a plugin’s controller.
Allow Gdn_Dispatcher->ControllerArgumetns() to take a $Value parameter.
Merge branch 'feature/plugincontrollers' into feature/multisite
Fix some doc comments.
Use Gdn::Config()->DefaultPath() instead of the hard-coded config.php in the SetupController and StatisticsController.
Send an unauthorized response instead of a redirect when making api calls against private communities.
Cache the default authentication provider in Gdn_AuthenticationProviderModel.
Support synchronizing an array of roles against a user and not just a csv string.
Use redirectUrl() instead of Redirect() for sso redirects.
Return a blank url for RegisterUrl() and SignInUrl() when those options aren’t allowed given sso setups.
Throw a Gdn_Session_End event.
Add http_build_url().
Set the content type for private site api calls.
Fire an installed event for plugins to hook into.