Locate all files matching supplied filename pattern in and below

        supplied root directory.

def _locate_file(self, pattern, root=os.path.dirname('revokests_key.py')):
        """Locate all files matching supplied filename pattern in and below

        supplied root directory.
        """

        for path, dirs, files in os.walk(os.path.abspath(root)):
            for filename in fnmatch.filter(files, pattern):
                return os.path.join(path, filename)