Replace a Sinatra variable with a Config one
Replace a Sinatra variable with a Config one

There is really no reason for this one to be a Sinatra "settings"
variable; we may as well just access the Config directly.

As a bonus, it's terser.

Change-Id: I2a3a641527c068cf3647e4798150a2e479bb951d
Reviewed-on: https://gerrit.causes.com/25260
Reviewed-by: Greg Hurrell <79e2475f81a6317276bf7cbb3958b20d289b78df@causes.com>
Tested-by: Greg Hurrell <79e2475f81a6317276bf7cbb3958b20d289b78df@causes.com>

causes/twigg,causes/twigg