'Appends directive to the end fo the file given by aug_conf_path.
.. note:: Not added to AugeasConfigurator because it may depend
on the lens
:param str aug_conf_path: Augeas configuration path to add directive
:param str directive: Directive to add
:param args: Value of the directive. ie. Listen 443, 443 is arg
:type args: list or str'

def add_dir(self, aug_conf_path, directive, args):

    self.aug.set((aug_conf_path + '/directive[last()    +    1]'), directive)
    if isinstance(args, list):
        for (i, value) in enumerate(args, 1):
            self.aug.set(('%s/directive[last()]/arg[%d]' % (aug_conf_path, i)), value)
    else:
        self.aug.set((aug_conf_path + '/directive[last()]/arg'), args)
