Use the Python provides macro to make a python-2 subpackage (#1399573).
    
    Also:
    - Mark license.txt as a license.
    - Depend on python3-paste and remove a no-longer-correct comment.
    - Move BuildRequires to top.
    - Create global for description and summary.
    - Don't remove the buildroot at the beginning of install.
    - Drop defattr from the files section.