Corrected require inside bind::zone
Corrected require inside bind::zone

Seems puppet doesn't like having a require with this form:
require => [Foo['bar'], undef].
The error was really… weird:
err: Could not retrieve catalog from remote server: Error 400 on SERVER:
comparison of String with :undef failed

This patch changes almost nothing, but allow the module to work properly
now…

This error wasn't detected before.

cloudbuy/puppet-bind,mcanevet/puppet-bind,camptocamp/puppet-bind,camptocamp/puppet-bind,cloudbuy/puppet-bind,ccin2p3/puppet-bind,raphink/puppet-bind,interlegis/puppet-bind,interlegis/puppet-bind,cyrus-mc/puppet-bind,mcanevet/puppet-bind,cyrus-mc/puppet-bind,trovitsys/puppet-bind,mvisonneau/puppet-bind,trovitsys/puppet-bind,mvisonneau/puppet-bind,ccin2p3/puppet-bind,raphink/puppet-bind