use versioned python dependencies
    
    test output:
        python-docker-2.3.0-1.fc26 BuildRequires:
         * python-coverage (python2-coverage is available)
         * python-flake8 (python2-flake8 is available)
         * python-mock (python2-mock is available)
         * python-requests (python2-requests is available)
         * python-setuptools (python2-setuptools is available)
         * python-six (python2-six is available)
    
        python2-docker-2.3.0-1.fc26 Requires:
         * python-requests (python2-requests is available)
         * python-six (python2-six is available)
    
    Signed-off-by: Tomas Tomecek <ttomecek@redhat.com>