CBD-1386:  add ubuntu-1204-x64 TOY builder

Change-Id: I3c75846ed55bf57d91b9e6ad8a411de79ef43471
Reviewed-on: http://review.couchbase.org/37896
Reviewed-by: Philip Labee <philip@couchbase.com>
Tested-by: Philip Labee <philip@couchbase.com>