Skip non-existing base directory and other updates.

[wilx]

There are some updates here in the branch. But the main change here is the addition of baseDir configuration to the validation set. This allows me to speed up execution of the checking goal when it is set up in parent of huge Maven projects tree. When such tree has many many files, like several node_modules directories, the directory scanning code goes through all of the files and never finds a matching file to verify. But with the baseDir options, if I set the value to, say, ${project.basedir}/src, I can return from the scanning code immediately and avoid scanning the entire tree without results.