Update file header and add NOTICE file

[rschwant]

This PR closes this issue: #321

The header files have all been updated to only include the license information, which is consistent with Apache 2.0 license recommendations.

The copyright is moved to a single NOTICE file and updated with latest advice from NOAA management for software releases of code like this one that are co-developed across different agencies.

[rschwant]

NOAA's websites are down today due to some maintenance, so don't worry about the tests failing they will work tomorrow

[bbakernoaa]

we could also follow what GFDL has been doing in their repositories. They add a disclaimer in the readme file for NOAA

Disclaimer

The United States Department of Commerce (DOC) GitHub project code is provided on an 'as is' basis and the user assumes responsibility for its use. DOC has relinquished control of the information and no longer has responsibility to protect the integrity, confidentiality, or availability of the information. Any claims against the Department of Commerce stemming from the use of its GitHub project will be governed by all applicable Federal law. Any reference to specific commercial products, processes, or services by service mark, trademark, manufacturer, or otherwise, does not constitute or imply their endorsement, recommendation or favoring by the Department of Commerce. The Department of Commerce seal and logo, or the seal and logo of a DOC bureau, shall not be used in any manner to imply endorsement of any commercial product or activity by DOC or the United States Government.

[rschwant]

Good idea, I'll add this to the Readme too