RAT-171: Add parsing of SCM ignores and enable exclusions in maven runs

* If configuration parameter 'parseSCMIgnoresAsExcludes' is set to true OR
  environment variable 'rat.parseSCMIgnoresAsExcludes' project basedir's SCM ignores are parsed for exclusions.
* Added tests and changed visibility of some helper methods, moved stuff in util packages.
* ExclusionHelper may parse ignore files. Certain comment prefixes are ignored. There's no syntax checking going on.
* Try out with: mvn -U -debug -Drat.parseSCMIgnoresAsExcludes=true


git-svn-id: https://svn.apache.org/repos/asf/creadur/rat/trunk@1672780 13f79535-47bb-0310-9956-ffa450edef68
8 files changed