changes required to support purging

In order for the ini file type to support purging,
the file path must be accessible on the class instance.

This patch was made to test some new functionality being added
to the inifile type
  https://github.com/cprice-puppet/puppetlabs-inifile/pull/25

It does effect backwards compat of this native type so its ok
to go ahead and merge.
Merge pull request #68 from bodepd/move_file_path_to_class

changes required to support purging