Fix python 2.6 support
Fix python 2.6 support

Kozea/WeasyPrint,andrewleech/WeasyPrint,marclaporte/WeasyPrint,jasco/WeasyPrint,Kozea/WeasyPrint,prepare/TestWeasyPrint,jasco/WeasyPrint,prepare/TestWeasyPrint,marclaporte/WeasyPrint,andrewleech/WeasyPrint