Use a custom copyright license matcher for RAT to allow usage of https links in copyright headers

A recent commit changed the license text in the copyright header on source
files to use https instead of http for refering to the license file. This
causes RAT tool to not match such copyright headers against
Apache License, Version 2.0. The use of "https" instead of "http" in the
copyright headers is considered valid as per the discussion here
https://mail-archives.apache.org/mod_mbox/ant-dev/201905.mbox/%3C87ftowunkc.fsf%40v45346.1blu.de%3E

This commit introduces a custom license matcher for RAT which matches
such copyright headers and considers them as "approved".
1 file changed