CBIDXT-16: queryport client and server.

BenchmarkStatistics        10000            101885 ns/op
BenchmarkScan1             10000            102560 ns/op
BenchmarkScan100            1000           2106819 ns/op
BenchmarkScanParallel      10000            127681 ns/op
BenchmarkScanAll           20000            100334 ns/op

client can be used by DP4 query and server can be used by indexer
application (scan coordinator).

Change-Id: I5b02ef8636950131129b230c3a96fb09e02b3616
Reviewed-on: http://review.couchbase.org/41175
Reviewed-by: Deepkaran Salooja <deepkaran.couchbase@gmail.com>
Reviewed-by: Pratap Chakravarthy <prataprc@couchbase.com>
Tested-by: Pratap Chakravarthy <prataprc@couchbase.com>