add BR python-markdown
    
    addressing:
    + ./manage.py test
    Traceback (most recent call last):
      File "./manage.py", line 10, in <module>
        from coprs import app
      File "/builddir/build/BUILD/copr-git-14.f7157e1/coprs_frontend/coprs/__init__.py", line 30, in <module>
        import coprs.models
      File "/builddir/build/BUILD/copr-git-14.f7157e1/coprs_frontend/coprs/models.py", line 2, in <module>
        import markdown
    ImportError: No module named markdown
    RPM build errors: