fix previous commit and add a compatibility handling for python 2.7
fix previous commit and add a compatibility handling for python 2.7

Freifunk-Rhein-Neckar/ffrn-expansion-map,mweinelt/ffrn-expansion-map,Freifunk-Rhein-Neckar/ffrn-expansion-map,mweinelt/ffrn-expansion-map,mweinelt/ffrn-expansion-map,Freifunk-Rhein-Neckar/ffrn-expansion-map