Add source option to 'generate deployment method' on abstract classes

@RunWith(Arquillian.class)
public abstract class AbstractTest
{
   @Test
   public void testa() {}
}

This should show no warning on 'missing deployment method' since it's a common pattern to have @Test's in a superclass with multiple sub classes that define deployments, but it's also a common pattern to have the deployment defined in a super class and multiple sub classes with different testing scenarios.

Given a abstract class
When there is no deployment method
Then give the 'source' option to 'generate deployment method'