CBIDXT-37 Refactor scan coordinator to use queryport interface

Refactored scan coordinator to use queryport server to receive
query requests such as scan, scanall and stats. Queryport listens
at tcp port 9998.

Change-Id: I543b490170968130756d8846ad8b1f3467f1cf03
Reviewed-on: http://review.couchbase.org/43033
Reviewed-by: Pratap Chakravarthy <prataprc@couchbase.com>
Reviewed-by: Sarath Lakshman <sarath@couchbase.com>
Tested-by: Sarath Lakshman <sarath@couchbase.com>