Simplify the top level licensing

[hyandell]

Summary

Simplifying the top level licensing

Description

As the original Postgesql driver source files refer to LICENSE, our having that license in THIRD-PARTY-LICENSES could be confusing. Given we use the same BSD-2-CLAUSE license, it's very easy to merge the two files together and remove any confusion someone might have from following an original file's source header back to the LICENSE file.

I've updated the LICENSE file and deleted the THIRD-PARTY-LICENSES file.

[wieck]

@hsuamz I don't think there is anything to discuss about licensing here. The existing code was and is covered under the PostgreSQL license, which is a derivative of the BSD 2-clause license. Since you don't own the copyright to that code, you won't be able to change the license.

What the discussion is about is the proper representation of copyright and code ownership. The way it reads in your repository suggests that AWS is the primary owner of copyright on most of the code. The reality is quite the other way around.

[davecramer]

I would also like to see a date on the amendment at the very least.

[hyandell]

I've taken another stab at the text to make the nature of the project more clear. Please let me know how that looks.

My general principles were:

1. I don't want this to look like it is passing itself off as the original project.
2. I want to clearly and respectfully explain the project relationships in the licensing; without it turning into a tome.
3. I want this all in LICENSE so that the existing PostgreSQL source header fits.

(@davecramer I wasn't sure what you meant by amendment. If you mean a year on Amazon's copyright, we don't typically put years on our open source copyright statements)