fix import_file() for Python 2.7
fix import_file() for Python 2.7

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