Delete obvious redirector app files
Remove more redirector-as-an-app content
Clean up tools/

Remove tools we don't use any more, document the ones we do.
Delete more redirector-as-an-app files
Delete Makefile and move relevant bits to jenkins.sh
Update README
Flesh out description of legacy assets
Merge pull request #925 from alphagov/remove-redirector-as-an-app

Remove code and files related to redirector as an app