Decision on final public license for repo

This repo was initialized with a [MIT License (spdx:MIT)](https://spdx.org/licenses/MIT) as this is the Permissive License used by the bitcoin-core community (see [COPYING], and basically the purpose of this project is to standup full nodes using `bitcoind`.

We clearly do not want to use a copyleft license with this project, however, there is an argument that in general Blockchain Commons as it's choice for permissive licenses should use the [BSD-2-Clause Plus Patent License (spdx:BSD-2-Clause-Patent)](https://spdx.org/licenses/BSD-2-Clause-Patent.html) as it adds an express patent grant and is an [OSI-Approved license](https://opensource.org/licenses/BSDplusPatent).

However, the Apache Foundation has listed this license as one of the [Category X](https://www.apache.org/legal/resolved#category-x) license, meaning it can't be used in Apache products. I'm don't completely understand the issue, but I've found some discussion at [Lesson learned from facebook and BSD+Patent](https://blog.cloudboost.io/lesson-learned-from-facebook-and-bsd-patent-17485bfbfd06), but Facebook describes it [differently](https://code.facebook.com/pages/850928938376556).

On the good side, Blue Oak Council lists this license is a [Gold](https://blueoakcouncil.org/list#gold), their 2nd highest rating.

The "Category X" problem may also challenge us if we choose the Apache 2.0 license for our standard Weak Copy Left license.

This whole area annoys me and I wish we could avoid it, but with the proliferation of submarine blockchain patents, we will need to create some policies here.

-- Christopher Allen