habitat_package: add files and dependencies properties

[clintoncwolfe]

Add support for listing installed files and dependencies of an installed package.

Approach:
Find hab pkg install location by running 'hab pkg env hab', look for PATH export, pick apart
Find deps by using hab pkg install location / origin / name/ version / release / TDEPS
Find files installed by using hab pkg install location / origin / name/ version / release / FILES and parsing

Partial work towards adding support finding the install root is in place on https://github.com/inspec/inspec-habitat/tree/cw/add-files-to-package-resource, but needs a change in train-habitat (enabling support for run_command) is needed.