Minor fix to prevent acv-form-data from being added to all comment forms

https://github.com/AdvancedCustomFields/acf5-beta/issues/198#issuecomment-42622017
Signed-off-by: Elliot Condon <e@elliotcondon.com>
Merge branch 'master' of https://github.com/AdvancedCustomFields/acf5-beta