Arvados

Currently, controller returns error messages like this:

request failed: http://localhost:8004/arvados/v1/containers/ce8i5-4zz18-t1qaidhvwn7rusu: 404 Not Found: Path not found (req-yewplazjko7817hghxxk)

The "http://localhost:8004" part can be confusing/misleading to someone who was expecting to connect to "https://ce8i5.arvadosapi.com". It also reveals a bit of detail about internal configuration, which might not be desirable (if the RailsAPI internal URL were an internal domain name instead of localhost, for example).

On the other hand, the internal URL (and the fact that the error originated from RailsAPI rather than controller itself) can be useful for troubleshooting.

• Change "http://localhost:8004" to "//railsapi.internal" in these error messages
• Remove the "http://localhost:8004" part entirely
• Make this behavior configurable