Skip create_profile if source is nil

Because customer_profile is assigned to a source, it is reasonable not to call `create_profile` when the source is nil.
Previously, `respond_to?` check implicitly checked the source is not nil.
Do not simulate create_profile for source with profile

Bogus gateway requires the source to provide an actual number, not a profile.
This fixes tests that give a mock card pretend to have profile.