Move wildfly-samples/jberet to a sub-module under jberet parent

Move https://github.com/chengfang/wildfly-samples to form a sub-module under jberet parent (https://github.com/jberet/jsr352).

The history and other metadata should be perserved during the move.

A good reference article on using git to achieve this:
http://gbayer.com/development/moving-files-from-one-git-repository-to-another-preserving-history/