adminport error code and error formating.

Change-Id: Id07e06ab6796d74db507a7b6cde65c5aa42c5c70
Reviewed-on: http://review.couchbase.org/38474
Reviewed-by: John Liang <johliang00@gmail.com>
Reviewed-by: Pratap Chakravarthy <prataprc@couchbase.com>
Tested-by: Pratap Chakravarthy <prataprc@couchbase.com>