Update Voluptuous requirement to version 0.6.

Voluptuous has a version 0.6 now which deprecates the any, match, and
required predicates and replaces them with Any, Match, and Required.
Update the minimum required version of Voluptuous and stop using the
deprecated predicates.

Change-Id: I554a6fda2c622a0b63f9247b1eae5eb494af225b
Reviewed-on: https://review.openstack.org/22167
Reviewed-by: Khai Do <zaro0508@gmail.com>
Approved: James E. Blair <corvus@inaugust.com>
Reviewed-by: James E. Blair <corvus@inaugust.com>
Tested-by: Jenkins