Add www.darwininitiative.org.uk to whitelist

This will be used for redirects from darwin.defra.gov.uk
Merge pull request #65 from alphagov/add_darwininitiative_to_whitelist

Add www.darwininitiative.org.uk to whitelist
[DFE] Add missing whitelist entries
Merge pull request #66 from alphagov/dfe_missing_whitelist_entry

[DFE] Add missing whitelist entry
Add www.lmiforall.org.uk to whitelist for ukces
Merge pull request #67 from alphagov/add_lmiforall_to_whitelist

Add www.lmiforall.org.uk to whitelist for ukces
Append the request path when the site has it set

This is useful where a site we are transitioning has moved to another site we
are transitioning, but on a sub-path, eg:
http://www.ukspaceagency.bis.gov.uk/*
became:
http://www.bis.gov.uk/ukspaceagency/*
before GOV.UK existed.

This feature means we can have the complex mappings in one place.