common: prefix and configuration.

- adjust url-prefix while fetching Cluster_info
- log-prefix for INFO, WARN.
- added back `adminport.listenAddr` config, parameter will be overriden by
  command line switch.

Change-Id: I38c948761acbe645a9eb217b8b3203d0decd8b2c
Reviewed-on: http://review.couchbase.org/44165
Reviewed-by: Sarath Lakshman <sarath@couchbase.com>
Reviewed-by: Pratap Chakravarthy <prataprc@couchbase.com>
Tested-by: Pratap Chakravarthy <prataprc@couchbase.com>