The file resource's `#content` method will return nil if the file
cannot be read for permissions issues. If you try to run a profile
that uses the `xinetd` resource without sudo privileges, InSpec
would try to call `#empty` on nil.
This change fixes this issue by checking for nil before checking
for emptiness.
Signed-off-by: Adam Leff <adam@leff.co>
Many of the resources are named as a top-level class with a fairly generic class name, such as "OS". This causes an issue specifically with kitchen-google which depends on a gem which depends on the "os" gem which itself defines an OS class with a different superclass. This prevents users from using TK, Google Compute, and Inspec without this fix.
Some mocked commands had their digest changed as well due to the new indentation, specifically in the User and RegistryKey classes.
I strongly recommend viewing this diff with `git diff --ignore-space-change`
to see the *real* changes. :)
