add FlashHash#each method, Gemfile, fix bacon issue

Hi, I wanted to be able to use this idiom in views:

  <% flash.each do |type, message| %>
    <div class="<%= type %>"><%= message %></div>
  <% end %>

so I added the each method to FlashHash and made this pull request. I also added a basic Gemfile based on test/test_helper.rb and fixed a bacon related issue.

Ciao
Andrea