FIX: Provide a default value for WorkflowTemplate::createAction() to prevent errors.
FIX: Provide a default value for WorkflowTemplate::createAction() to prevent errors.

The $definition argument is sometimes passed null, which violates the WorkflowDefinition type hint (at least in PHP 5.3.19). By making the default argument null, this issue seems to go away.

silverstripe-terraformers/advancedworkflow,silverstripe-australia/advancedworkflow,Internetrix/advancedworkflow,Internetrix/advancedworkflow,dnadesign/advancedworkflow,silverstripe-australia/advancedworkflow,dnadesign/advancedworkflow,icecaster/advancedworkflow,silverstripe-australia/silverstripe-advancedworkflow,silverstripe-australia/silverstripe-advancedworkflow,silverstripe-terraformers/advancedworkflow,icecaster/advancedworkflow