def whitelisted_params
      whitelist = params_for_resource(:sign_up)

      whitelist.inject({}) do |coll, key|
        param = omniauth_params[key.to_s]
        coll[key] = param if param
        coll
      end
    end
def whitelisted_params
      whitelist = params_for_resource(:sign_up)

      whitelist.inject({}) do |coll, key|
        param = omniauth_params[key.to_s]
        coll[key] = param if param
        coll
      end
    end
derive allowed params from the standard devise parameter sanitizer