Better handling when target Object Storage service lacks a service-key

[joshisa]

boilerup@macrox ~ $ cf os auth myObjectStorage
Authenticating with org joshisa@us.ibm.com / space dev as joshisa@us.ibm.com...

FAILED
Failed to fetch a new set of credentials (Try running `cf login`): Failed to locate target service's credentials: Could not find credentials for target service

boilerup@macrox ~ $ cf service-keys myObjectStorage
Getting keys for service instance myObjectStorage as joshisa@us.ibm.com...
No service key for service instance myObjectStorage

boilerup@macrox ~ $ cf create-service-key myObjectStorage myCreds
Creating service key myCreds for service instance myObjectStorage as joshisa@us.ibm.com...
OK

boilerup@macrox ~ $ cf os auth myObjectStorage
Authenticating with org joshisa@us.ibm.com / space dev as joshisa@us.ibm.com...
OK

Authenticated with myObjectStorage
boilerup@macrox ~ $

Observation: Failure to fetch a new set of credentials provides guidance for trying cf login. However, the root cause can also be the lack of a service-key as well.

Suggestion(s):

1. Update the error message to also guide users to investigate whether a service-key exists and to leverage cf create-service-key if one is not present.

2. Perhaps we could provide a flag (or simply default) to auto-creation of a service-key for the service instance under investigation.