Try and bring ACNW and ACUS together through:
 1. Configuration values
 2.

Added configuration settings:

Copyright holder in footer
 - config.copyright (string)

Used to set range on min and max player in creating games
 - config.playerMin (positive integer)
 - config.playerMax (positive integer)
 - config.minPlayersFloor (positive integer)
 - config.minPlayersCeiling (positive integer)
 - config.maxPlayersFloor (positive integer)
 - config.maxPlayersCeiling (positive integer)

Used by ACUS on its hotel page to allow people to book in its
block of rooms:
 - config.hotelBookingCode (string)
 - config.hotelBookingUrl (string)
 - config.hotelBookingLastdate (date)

Resolves: #155, #158, #160, #161
See also: #159

Instead of sticking configuration.abbr in local variables of acnw and
acus, which are essentially inverted Boolean flags, check against its
values of 'acus' or 'acnw' directly. It's simpler, clearer, and allows
for adding a third (even if only synthetic) site.

Resolves: #155, #158, #160, #161
See also: #159

Wanted to pick up hotel booking code and link and book by date, as
we change those apparently every year. And also wanted to pick up
the contact email from settings.

Resolves: #163, #155, #158, #160, #161, #159

Part of the changes. Guy's PR review noted to remove this.

Don't know how it survived in here with all the other changes to
config in the past, but it's a good thing to make it gone.