MB-13776 queryport: Return human readable error on server conn loss
MB-13776 queryport: Return human readable error on server conn loss

Whever indexer server goes down, queryport scan client returns io.EOF.
Changed it to return a human readable error message.

Change-Id: I6417d49b682c0d124af796b10ced9355d901c672

jchris/indexing,jchris/indexing,jchris/indexing,jchris/indexing