Spin up our own PostgreSQL server and use it
Add a marker for any test that uses the database
Create an escape hatch for using an existing database
Merge pull request #258 from dstufft/rework-database

Reworking database fixtures
Add support for user sessions
Add a basic framework to handle user authentication
Implement CSRF
Rework the session handling to use a dispatch_view decorator
Store our sessions inside of redis

* Use msgpack to serialize the sessions for more compact
  storage and for faster serialization/deserialization
* Move the session cycling support into our RedisSessionStore
* Expire our redis sessions after 12 hours, but renew the session
  on every interaction with Warehouse
Use warehouse.utils.random_token for our CSRF tokens
Support ?next= urls on login to control the redirection
Add a page that allows users to log out of their session
Log when an error occurs trying to verify the user's password
Enable translations of the login form
Add tests for all the new functionality