Move add functionality into a separate tool.

Rat is a Release Audit Tool.  It should only report on the what exists and not make changes.

The change option -A or -a causes problem in that it creates files that exist in the source tree and leaves other tell tale signs that it was run.  These tend to get in the way of cleanly generating data for the reports.

This proposal is to extract the code that adds headers into a separate tool in the tools package.  This will simplify the mainline code and allow independent progression on the update functionality.