Add support for storing the current delay in Redis.

This will replace the storing of it in a dictionary in display_utils
shortly.

Change-Id: If2cadcb920f9ab4b9643073240052984f84b81c6
Rename method to avoid clash.

Thus ensuring that the right one gets called, though as they're usually
called via their decorators, this probably wouldn't have been an issue.

Change-Id: I3bb62eb3e85231022f8e0ad6ea9e7f16b621432e
Remove duplicate test.

This appears to have been duplicately defined.

Change-Id: I5537573253a648935ef20f02cf71901288d5bf90
Remove support for the screens.

These weren't controlled from poltergeist last year, and aren't
going to be this year either.

Change-Id: I5e6db2a7dca0d5f262ef2dba3e810e5b239dc95e
Separate out commands from database wrappers.

This provides a clearer separation between the portions of the code
which wrap access to redis and those which pump that data outwards.
Whatever outwards is going to mean this year.

This also separates the tests, and exposes 4 more tests which had
name clashes and were thus hiding each other.

Change-Id: I264e79338039b434728f14fa1c47f073550742ed