Added support for authentication methods.

This commit introduces `/api/v1/auth/login` and `/api/v1/auth/logout`. These methods make use of the internal storage system to fake a session. Note that the `nav` object will be populated by a separate API method as @jmeas and I previously discussed.
This was the object you added in https://github.com/jmeas/rave/commit/d06e14ab9272404910e1a510fa1b8bfe145445aa#diff-0acc8661075fb39da38bb49c9adcd98dR47.