Ember serialize output response

I want the response to be in this format:

{"password"=>"[FILTERED]", "email"=>"admin@admin.com"}

However, this is the response that I'm getting now:

{"user"=>{"password"=>"[FILTERED]", "email"=>"admin@admin.com"}}

Code: http://ift.tt/1Xv7Dye

Any idea how to fix this?