Add a circuit breaker to Content API client
Put circuit breaker behind a switch
Add metric for requests failed by circuit breaker
Return a Service Unavailable response if the Content API circuit breaker is open
Merge branch 'master' into use-a-circuit-breaker-for-content-api
Merge branch 'master' into use-a-circuit-breaker-for-content-api
Merge pull request #5752 from guardian/use-a-circuit-breaker-for-content-api

Add a circuit breaker to Content API client