Update variable name definitions to include any traits passed

Support creating multiple registered factories when using traits
example:
```ruby
describe User do
  describe '#some_method' do
    with :user, :without_first_name
    with :user, :without_last_name
    it 'works as expected' do
      user_without_first_name.some_method
      user_without_last_name.some_method
    end
end
```