update NOTICE for 0.13.1 release with RocksDB BSD+patents license

Based on the following email, we are updating the NOTICE accordingly:

From: Chris Mattmann <mattmann@apache.org>
Date: Sat, Jul 15, 2017 at 9:56 AM
Subject: Facebook BSD+patents license and Apache products
To: legal-discuss@apache.org

Hi,

As some of you may know, recently the Facebook BSD+patents license has been
moved to Category X (https://www.apache.org/legal/resolved#category-x).
Please see LEGAL-303 [1] for a discussion of this. The license is also referred
to as the ROCKSDB license, even though Facebook BSD+patents is its more
industry standard name.

This has impacted some projects, to date based on LEGAL-303
and the detective work of Todd Lipcon:

Samza, Flink, Marmotta, Kafka and Bahir

(perhaps more)

Please take notice of the following policy:

o No new project, sub-project or codebase, which has not
used Facebook BSD+patents licensed jars (or similar), are allowed to use
them. In other words, if you haven't been using them, you
aren't allowed to start. It is Cat-X.

o If you have been using it, and have done so in a release,
you have a temporary exclusion from the Cat-X classification thru
August 31, 2017. At that point in time, ANY and ALL usage
of these Facebook BSD+patents licensed artifacts are DISALLOWED. You must
either find a suitably licensed replacement, or do without.
There will be NO exceptions.

o Any situation not covered by the above is an implicit
DISALLOWAL of usage.

Also please note that in the 2nd situation (where a temporary
exclusion has been granted), you MUST ensure that NOTICE explicitly
notifies the end-user that a Facebook BSD+patents licensed artifact exists. They
may not be aware of it up to now, and that MUST be addressed.

If there are any questions, please ask on the legal-discuss@a.o
list.

Thanks.

Cheers,
Chris Mattmann
VP Legal Affairs