Log and follow 301 redirects

[apetro]

When the proxied resource responds with a 301 Moved Permanently,

• Log once noting the update that ought to be made to the config
• Follow the permanent redirect so the integration keeps working

(Raising issue after experience of MyUW's person directory search integration breaking because the backing service started 301ing expressing its permanent switch from http to https.)

[vertein]

👍