Creates new WSGIService class which keeps base API sercice
initialization functionality and serve flask application. Also
it will configure application for wsgi container[1].
Also creates new `cmd` directory for storing console scripts.
[1] https://governance.openstack.org/tc/goals/pike/deploy-api-in-wsgi.html
Related-Bug: #1525218
Change-Id: Ia64228c47a79a3008d435e8323a964f2bc45dfa7