Allow custom additional to each model

[AshaLiu]

All attributes inside additional will work on each model, but in my case, I want to generate models with different additional. For example, some model need enable paranoid，the others does not need.

Would it be possible to provide an api that will allow the user to customize the model additional.

eg：

additional: {}, // default global setting
customAdditional: {
   tableName: { ...additional }
}