upr client: Log error message and retry for obtaining upr mutation

If upr client does not receive a mutation message within 1 minute,
it logs an error message and waits for upr message. This will help
in debugging issues related to upr server not sending mutations.

Change-Id: I197635d80755eb1b73c5b960419fca51b9fd8ca0
Reviewed-on: http://review.couchbase.org/36741
Reviewed-by: Sriram Melkote <siri@couchbase.com>
Tested-by: Sarath Lakshman <sarath@couchbase.com>