recommend installing deps using dnf builddep
    
    Fixes #74. The `pip install` command currently fails unless you have gcc
    and swig and other tools installed. At this point it's easier to
    recommend just installing the dependencies using dnf, rather than
    installing everything needed to set up a virtualenv and then setting up
    the virtualenv.
    
    This also has the advantage of more closely matching how WaiverDB is run
    in production (which is using Fedora packaged dependencies rather than
    ones downloaded and built from PyPI).