Move finding class and pass query string
Making explicit 'If it is a special case...'
If old URL has query string and is not BL, use generic map key mapper

(In this commit, this is currently a copy of BL mapper)
Tests for DECC location config

These pass as expected.
Non BL URLs with query strings now have a default class to create config

Including tests for DECC mappings with query strings.
Including the redirect maps in the decc.conf

And also instructions in the README for how to create the config file, including how to do it when it has redirect maps.