Travel offers are cached to S3.

Just in case the feed breaks again.
Removed hacky logging
remove reference to util/common
fixing tests
just remove common spec
remove unused common util
Adding metrics to the Travel Offers cacher.
Fixed typos.
use async
Moved the TravelOffersCacheAgent to admin

For great singularity
Added TravelOffersCacheJob to Admin Tasklist
Renamed test
Merge remote-tracking branch 'origin/master' into persistTravelFeed

Conflicts:
	common/test/common/GuardianConfigurationTest.scala
Merge pull request #4988 from guardian/persistTravelFeed

Persist travel feed
fix rows
Merge pull request #5008 from guardian/admin-tweaks

Fix static assets view
Merge pull request #5005 from guardian/remarketing-async

Use async version of remarketing code
adding exports
don't rename assign to extend
Merge pull request #4974 from guardian/remove-old-common-util

Remove old common util