Feature/login

@hab278 I found a clash in instance vars here so I renamed this one.

Also as it was this will not update attributes for an existing user so I changed it to as it is below. The first_or_intitialize followed by update_attributes means we only have one database interaction. I'm open to other implementation suggestions.

```ruby
  def nyulibraries
    @user = find_user_with_or_without_provider.first_or_initialize(attributes_from_omniauth)
    @user.update_attributes(attributes_from_omniauth)

    if @user.persisted?
      sign_in_and_redirect @user, event: :authentication
      set_flash_message(:notice, :success, kind: "NYU Libraries") #if is_navigational_format?
    else
      session["devise.nyulibraries_data"] = request.env["omniauth.auth"]
      redirect_to root_path
    end
  end

  def find_user_with_or_without_provider
    @find_user_with_or_without_provider ||= (find_user_with_provider.present?) ? find_user_with_provider : find_user_without_provider
  end
```