Add FaciaResult trait with case classes
Try to recover from an AmazonS3Exception otherwise throw the exception
Add BackendError which is returned by ApiClient
Fix all the tests
Change safeMeta to lazy val
Better case match
Merge branch 'better-error-handling'

Conflicts:
	src/main/scala/com/gu/facia/client/ApiClient.scala
	src/main/scala/com/gu/facia/client/models/Collection.scala