CBD-1383:  restore rel-2.5.1 to 2.5.1 release point, except couchdb uses branch "MB-11187"
           add override manifests identical to release, but v8 uses revision="3.21.17-couchbase"

Change-Id: I90899b8a1346201d3fec8627f1ee02c324cd49e8
Reviewed-on: http://review.couchbase.org/37655
Reviewed-by: Chris Hillery <ceej@couchbase.com>
Tested-by: Chris Hillery <ceej@couchbase.com>