use verbatim license texts

[smola]

We are adding copyright holder name and year to the licenses text.
But instead of adding a copyright notice, we were just editing
appendixes with instructions about adding the notice, not the notice
itself. This is not valid.

Copyright notice is usually added to source code file headers in comments,
to README or to a NOTICE file.

See some examples of applying these licenses:

• Apache Foundation uses the verbatim text (without replacing anything), then
  they add copyright headers to files, see:
  https://github.com/apache/spark
  https://github.com/apache/httpd

• Android uses a custom NOTICE file, where they add their copyright notice,
  and then they add Apache License 2.0 terms and conditions without the appendix, see:
  https://android.googlesource.com/platform/dalvik/+/froyo/NOTICE
  https://android.googlesource.com/platform/dalvik/+/master/NOTICE

Since hacktoberfest started, we got a lot of pull requests changing from verbatim licenses to these versions, or updating the year. I've closed most of them since they're pointless, but it would be better if we sort this out in the guide to avoid future confusion.

[vmarkovtsev]

+1 as long as it is legally valid.

[smola]

@vmarkovtsev it is legally valid in terms of LICENSE text, however, I think we still need to include a proper copyright notice to our projects (either source code headers, NOTICE file, explicit LICENSE appendix or README.md, I'm not sure where).

[mcuadros]

Can you clarify how this works? I don't like the idea of having headers.

[smola]

@mcuadros IANAL (this would require a lawyer/expect confirmation before acting on it, do not hold me accountable for legal decisions!), here's my understanding:

A copyright notice is required to apply a license properly. These are the existing options, which are not mutually exclusive, more than one can be combined:

• A copyright notice can be embedded with the license text itself. This is quite common in very short licenses (MIT example, BSD-3 example.
• Use a NOTICE file including the copyright notice, including any required notice about 3rd party licenses. This is what Apache Foundation does.
• Adding it at the bottom of README?
• Add a copyright notice to the header of each file, in a comment. This is recommended by the FSF and ASF. It is not required for the license to have effect, it is just a recommendation to remove some legal uncertainties.

But clearly, the Apache/GPL LICENSE text itself is not a copyright notice, and the appendix of the Apache License isn't either.

[mcuadros]

Let's use NOTICE + LICENSE file.

[dpordomingo]

Is this ready to be merged?

[smola]

@dpordomingo Nope. Closing. The definitive version of this was absorbed by #273