Support db ports other than the default (3306). We now always specify the port in the db url. #503444

just an in progress commit. this branch introduces some new dispatchers to handle some of the tricky logic we've found in classes.

A bevy of subtle fixes. Primarily #597750 because we no longer 'do' site id. Also fixed restore which left you with a broken site, and handled the fact that
the drush_config_file function would only give us the right value when we were bootstrapped to that level.

this meant we couldnt regenerate the site drushrc.php until we'd bootstrapped to drupal_configuration, which meant during restore it would always use the old values.

Also when the restore task finished, the save_site_config malarky would end up writing the old values over the correct ones.

If the master server -> aegir_root db connection is happening on the local server, use 'localhost' as the host name.
all the grants will still happen using the remote_host of the server.

Remove the 'magic' from services. they now access the server properties through the $this->server reference created during __construct.

the singular filesystem object now.

Sync is now a method of the server class, with a helpful method associated
to the services that redirect to the service's server.

Sort of fix site import, which also verifies now. Introduce d()->site_path instead of concatenating everywhere.

New, more-flexible, MySQL grant_host(). No need to check if db verify is on a server, it always is. Whitespace.

Removed the provision_service function, and introduce service handler subscriptions in the environment objects.

Instead of provision_service('type') you now use d()->service('type') to access the service object.
The context object returned by d() now manages which context object's service to return, based
on the internally managed subscriptions.