fix classifiers in setup.py for Python 3
fix classifiers in setup.py for Python 3

BubuLK/sfepy,vlukes/sfepy,BubuLK/sfepy,BubuLK/sfepy,vlukes/sfepy,rc/sfepy,sfepy/sfepy,rc/sfepy,rc/sfepy,sfepy/sfepy,sfepy/sfepy,vlukes/sfepy