Enhancement deuce context swift storage url

- Stores the storage_url in the Deuce Context under deuce.context.openstack.swift.storage_url
- Fixes the mocking for Swift Client so that it is enabled via a single variable in config.py so the user does not need to modify test code to turn it on/off.

Depends on PR #82 

JIRA #CBDEUCE-153
We shouldnt require username, password even for testing right? We just supply some mock data in the headers and that should do it.