The release_and_deploy function and several proxy plugin scripts call fn-plugin-property-* helpers without sourcing `plugins/common/property-functions`, producing `command not found` errors during deploys. Source the helpers from `plugins/common/functions` and from each proxy plugin entry point that consumes them.
When developing Dokku, it is useful to use a real domain to test actual functionality. This is impossible if the domain is hardcoded to dokku.me in testing.
The URLS file is no longer necessary as urls are now generated directly from the app VHOST file.
This also moves all the url generation logic to the domains plugin.
