Add .ruby-version file

Now we can force the app to use Ruby 2 with rvm and rbenv
Add pry gem to debug
Add gems to acceptance specs

Add:
 - capybara
 - capybara-webkit
 - turnip
Add bootstrap flash helper
Add a home page and improve user login and CRUD
Add shared_connection configuration to the specs

Link to why:
  http://blog.plataformatec.com.br/2011/12/three-tips-to-improve-the-performance-of-your-test-suite/