Added a licenses/ directory to core which contains a sha1 file for each JAR
dependency, and one or more LICENSE files and one NOTICE file for each
project.
Also adds dev-tools/src/main/resources/license-check/check_license_and_sha.pl
which checks that the licenses/ dir is up to date during a mvn verify,
and which can be used to update the sha1 files when upgrading dependencies.
Closes#2794Closes#10684Closes#11705
Clinton Gormley