Set permissions on existing directory

Previously, an existing directory would not have its permissions
modified by the __directory type. This change removes exiting early when
$state_is matches $state_should
directory permission explorers

The group, mode, and owner are now pulled from a explorers. If the
desired value matches the existing value, then no code is executed.

If the recursive flag is set, the permissions are applied every run.
Initialize variables to empty string

Set mode, group, etc. to an empty string to ensure that no external
environment variables can leak in.
Merge pull request #155 from statianzo/directory-owner

Set permissions on existing directory