Memcached backend for oslo.cache for oslo-incubator

Memcached backend for oslo.cache

Replace httplib calls with python-request for Glance Client

The idea is to migrate all httplib calls into something based on python-requests[0]. Since python request already takes care of most of the things related to http requests, headers and different aspects around it (chunks, keep-alive, gizp, json, etc), it could be a good thing to migrate this, and other OS clients t...