Remove arbitrary resource dependency.

Summary:
It is possible to set up an openvpnserver and want to provide
client-specific configurations without configuring the client through the
puppet-openvpn module. Removed the dependency from client_specific_config.pp

Test Plan: rake tests good.

Reviewers: pfrost, #developers

Subscribers: pfrost, jbowman

Maniphest Tasks: T136

Differential Revision: http://phabricator.macprofessionals.lan/D193