Fix import_mappings glob argument in load.sh

* The mappings live in redirector/data/mappings, not redirector/mappings
* They're CSVs, not TSVs
Merge pull request #4 from alphagov/fix-mappings-load-sh

Fix import_mappings glob argument in load.sh
Merge commit '67a8941a47b12e547963c9493aac410ceee72f7d' into HEAD