Take `table_name_prefix` into account

If a `table_name_prefix`has been setup it should not appear in the model name.

Currently if there is a prefix setup like `pr_` it will appear in the generated file name & model name:

pr_account.rb:
```ruby
class PrAccount < ActiveRecord::Base
end
```

It would be nice to have an option that can be passed specifying the prefix so it can be removed.