Add Automated Validation of Copyrights

[romeara]

Add automated validation that copyrights be present in all files. This requirement should be included in contributor documentation, and checks for it should be added to builds, including those run prior to accepting pull requests.

One way of automating this is the Checkstyle RegexpHeaderCheck Rule, with a header specification file such as:

/\*$
\W\* Copyright \d\d\d\d StarChart-Labs Contributors (https://github.com/StarChart-Labs)$