Enhancement test context unified

Depends on PR #81
In response to https://github.com/rackerlabs/deuce/pull/80#discussion_r16298987

- Moves the setup of the Deuce Context to the FunctionalTest's setUp()
- Individual tests that need to modify this, like the Swift tests - will need to still import it
- Swift main test now uses its setUp to add the openstack data
- Swift invalid token test temporarily saves the token and puts an invalid token in for the test, then restores the token at the end
do we want to put storage_url in the context, as well? We cant instantiate the driver otherwise.