Remove __init__ from slots in ExcelFormula.py for Python 3.3 compatibility
Remove __init__ from slots in ExcelFormula.py for Python 3.3 compatibility

bopo/tablib,alex/tablib,godfreyy/tablib,kennethreitz/tablib,enzochiau/tablib,leohmoraes/tablib,zhengzhihust/tablib,steveb/tablib,bopo/tablib,whix/tablib,whix/tablib,tommyanthony/tablib,mloesch/tablib,enzochiau/tablib,klothe/tablib,mloesch/tablib,klothe/tablib,leohmoraes/tablib,screwt/tablib,godfreyy/tablib,steveb/tablib,screwt/tablib,zhengzhihust/tablib