It was a moment on pain in my arse which was resulted from 10+ hours of debugging nikola and heroku services to get by static blog hosted automatically using travis CI. The benefits of learning heroku services were exemplary (In which I've learned much more about the internal architecture in this fiasco) which outweighs the drawback of complete failure.
Bottom Line: you can't serve a web app on heroku in a smoother way unless it supports wsgi.
PS: Feel free to use heroku to expose your flask service.
Mrityunjay