CBIDXT-90: dataport is refactored out as a sub-package.

so that it can be used not only by indexer but also by coordinator, XDCR
etc ...

Change-Id: I48fd6f94ea8d58f8c8510e9057303d021b1305a3
Reviewed-on: http://review.couchbase.org/39940
Reviewed-by: John Liang <johliang00@gmail.com>
Reviewed-by: Deepkaran Salooja <deepkaran.couchbase@gmail.com>
Reviewed-by: Pratap Chakravarthy <prataprc@couchbase.com>
Tested-by: Pratap Chakravarthy <prataprc@couchbase.com>