MB-12594: Add goxdcr

Change-Id: I72f2e2a250cf2fb19ef981ea2f4e0e7f40cdf1a9
Reviewed-on: http://review.couchbase.org/42999
Reviewed-by: Chris Hillery <ceej@couchbase.com>
Tested-by: Chris Hillery <ceej@couchbase.com>