Update flask_swagger.py
Update flask_swagger.py

Support Python 3.4
Navisite/flasgger,rochacbruno/flasgger,lorehov/flasgger,arnaldur/flask-swagger,Navisite/flasgger,flasgger/flasgger,litnimax/flask-swagger,lorehov/flasgger,flasgger/flasgger,talitarossari/flasgger,talitarossari/flasgger,ibratoev/flask-swagger,lorehov/flasgger,flasgger/flasgger,alejoar/flask-swagger,talitarossari/flasgger,Navisite/flasgger,rochacbruno/flasgger,flasgger/flasgger,rochacbruno/flasgger,Navisite/flasgger,lorehov/flasgger,gangverk/flask-swagger