CBD-1425:  add 3.0.0beta support for windows builders

Change-Id: I80d337adaca0044146d222aada1ddd52db855355
Reviewed-on: http://review.couchbase.org/41952
Reviewed-by: Philip Labee <philip@couchbase.com>
Tested-by: Philip Labee <philip@couchbase.com>