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
@TheSriram - for normal testing, no. Using the mock just works. However, if one wants to use the real swift client during testing then a username/password is required. That is the only purpose for this portion - to allow testing using a real swift backend.