Add redirection handling to openstack.session.Session

The requests lib follows some browser patterns where it will redirect POSTs
as GETs for certain statuses which is not want we want for an API.
See: https://en.wikipedia.org/wiki/Post/Redirect/Get

Partially implements blueprint: rest-client
Change-Id: If8593df64bd5ff9bf3b41f990b3c0b2dcfdbbda4
Merge "Add redirection handling to openstack.session.Session"