Add Apache license header to core files
Adjust test cookbook to use loopback device

Adjust our luks_test cookbook to use a loopback device instead of
another virtual disk. This makes our tests more portable with regards to
the various test-kitchen providers
Add additional required packages

Add additional required packages based on the following document

- http://wiki.centos.org/HowTos/EncryptedFilesystem
Merge branch 'use-loopback-device'