Rename redirector

The only breaking change here is in 52db97f which changes the directory that the app expects the transition-config (nee redirector) repo to be checked out to. This change will necessitate tweaking of the Jenkins jobs on deploy.production and deploy.preview which have knowledge of the directory names soon after this change is deployed. They are already working with the new repo name because GitHub redirects the relevant requests.
There's only transition left (the "transition-centric" was meant to indicate that the sites also existed for redirector). How about "A view over site yaml"?