* gnu/services.scm (activation-script): Return a <program-file> rather
than a <scheme-file>.
* gnu/deploy.scm (guix-deploy): Remove handling for '--system'.
(show-help): Remove documentation for '--system'.
(%default-options): Remove default setting for 'system'.
* guix/scripts/deploy.scm (load-source-file): Enumerate and include all
submodules of (gnu machine) when loading the provided deployment
specification.