(maint) Fix failing spec test with Puppet 3.3.0-rc2

(maint) Fix failing spec test with Puppet 3.3.0-rc2

Without this patch the stdlib spec tests are failing against recent
versions of Puppet.  The root cause of this problem is a change in the
behavior of create_resources in Puppet 6baa57b.  The change in behavior
caused the :name key to be omitted from the hash returned by
Puppet::Parser::Resource#to_hash which in turn is causing the test
failure.

This patch addresses the problem by updating the test to match the
description of the example.  Only the attribute :ensure is checked
instead of the full hash itself.