New port, www/py-flask-api: Browsable Web APIs for Flask

WWW: http://www.flaskapi.org/

https://github.com/tomchristie/flask-api

PR: 217950
Submitted by: daniel@blodan.se (maintainer)
Approved by: swills (mentor, implicit)
Differential Revision: https://reviews.freebsd.org/D10252