Drop Redis requirments

To move forward, we need to drop Redis. Right now, it does not make
sense to have Redis in our API layer. The right location is the having
payload-server interface with it.  Until we add the server side of
payload, we'll remove it from the API.

Change-Id: I93d767b2bd1ce09075db6db2bd11bc9bbccc1ab4
Signed-off-by: Paul Belanger <paul.belanger@polybeacon.com>