add Devise based authentication system, devise view also generated
using simple_form, also Change Devise form with simple_form style

rails generate simple_form:install --bootstrap
       exist  config
      create  config/initializers/simple_form.rb
      create  config/locales/simple_form.en.yml
      create  lib/templates/erb/scaffold/_form.html.erb
-----------------------------------------------------------------------------------
  Be sure to have a copy of the Bootstrap stylesheet available on your
  application, you can get it on http://twitter.github.com/bootstrap.

  Inside your views, use the 'simple_form_for' with one of the Bootstrap form
  classes, '.form-horizontal', '.form-inline', '.form-search' or
  '.form-vertical', as the following:

    = simple_form_for(@user, :html => {:class => 'form-horizontal' }) do |form|
Fix bug which only allow first user email blank, also clean Gemfile.lock
Add some hint to deploy Cloud-Foundry
Upgrade to devise 3.1.1