Fix Puppet Provisioner crash when HieraConfigPath or ManifestDir is specified

Prevents the following error,
Build 'amazon-instance' errored: template: tpl11:1:103: executing "tpl11" at <.HieraConfigPath>: HieraConfigPath has arguments but cannot be invoked as function
Merge pull request #730 from sudharsh/txt_template_fix

provisioner/puppet: fix crash when HieraConfigPath or ManifestDir is specified in the config file.