CBD-1425:  add 3.0.0beta support for windows builders

Change-Id: Ibd06543b2cb49cfb3d0f62776803df64515cf600
Reviewed-on: http://review.couchbase.org/41953
Reviewed-by: Philip Labee <philip@couchbase.com>
Tested-by: Philip Labee <philip@couchbase.com>