MB-12087: Include LICENSE for sample data in 3.0.0 manifest

Change-Id: Idec8285c7d6faf0c7fa769d565776e03beeaed37
Reviewed-on: http://review.couchbase.org/41095
Reviewed-by: Philip Labee <philip@couchbase.com>
Tested-by: Chris Hillery <ceej@couchbase.com>