run spec_standalone to support old and current rake tasks

Latest bundle seems to not invoke :spec_standalone from :spec,
so invoke it directly. This ensures the harness runs regardless
of which bundle is installed.
add tools for working with mercurial repositories
update all packages in base image at build-time
add host and dig commands to devenv
add ftp and tftp clients

These are useful for testing other services.
use the "semi-official" fedora 20 base image