CBLT-271: use android target 4:  "android-19"

Change-Id: I6e88c32eee09ef7f8673536f89799aafb552fc5d
Reviewed-on: http://review.couchbase.org/36651
Reviewed-by: Philip Labee <philip@couchbase.com>
Tested-by: Philip Labee <philip@couchbase.com>