Tokenization occurs both on create and update regardless of config

[nishimura-d]

In "Usage" section of README, 2 cases are described:

• To tokenize the password column on updates, add this to your UsersTable:
• If instead you wanted to have it create a token both on account creation and credentials update:

But actually tokenization occurs on create in 1st config.
implementedEvents config has no effect.

This is because the return value of Behavior::implementedEvents() has Model.afterSave if afterSave() method exists.
Maybe own implementation of TokenizeBehavior::implementedEvents() is needed.