title: On project task created do not send email
body: <p>By default subscribers get email messages once the new task in a project is created. How it can be tailored so that unless the projects has checkbox "Send e-mail on new task" checked it will not send e-mails on new task?</p>
  
  <p>I know how to add a custom field to project.project model. But don't know the next step.</p>
  
  <p><strong>What action to override to not send the email when a new task is created and "Send e-mail on new task" is not checked for project?</strong></p>