General cleanup of the specfile
    
     - python_sitelib was defined but never used
     - _with_python3 was True, so I removed the ifs
     - python3_pkgversion is defined on both Fedora and EPEL
     - %{py3dir} is deprecated and not needed here
     - use %pyX_build and %pyX_install macros, stop using %{__python}
     - run tests against the installed version
     - some cruft removal