title: Can not start rails server after changing gem file
body: <p>I just started the Ruby on Rails Tutorial by Michael Hartl. I am currently trying to get the exact same gems versions (listing 1.5 in the book) he uses to avoid future problems. I managed to run bundle update and bundle install with no problems but when I try to start the server by rails server I get error you will see below.</p>
  
  <p>The only main difference I can spot between his dev environment and mine is that I use rbenv and set the local ruby version for the project to 2.0.0-p353, and he uses RVM with ruby version 2.0.0. Could this be causing the problem? I can't find a ruby 2.0.0 version (without any -p...) on rbenv.</p>
  
  <p>Thank you for your help!!</p>
  
  <pre><code>  =&gt; Booting WEBrick
  =&gt; Rails 4.0.5 application starting in development on http://0.0.0.0:3000
  =&gt; Run `rails server -h` for more startup options
  =&gt; Ctrl-C to shutdown server
  Exiting
  /Users/eduardopoleo/Desktop/rails_projects/first_app/config/environments/development.rb:1:in `&lt;top (required)&gt;': undefined method `configure' for #&lt;FirstApp::Application:0x007ff71196dee8&gt; (NoMethodError)
      from /Users/eduardopoleo/.rbenv/versions/2.0.0-p353/lib/ruby/gems/2.0.0/gems/activesupport-4.0.5/lib/active_support/dependencies.rb:229:in `require'
      from /Users/eduardopoleo/.rbenv/versions/2.0.0-p353/lib/ruby/gems/2.0.0/gems/activesupport-4.0.5/lib/active_support/dependencies.rb:229:in `block in require'
      from /Users/eduardopoleo/.rbenv/versions/2.0.0-p353/lib/ruby/gems/2.0.0/gems/activesupport-4.0.5/lib/active_support/dependencies.rb:214:in `load_dependency'
      from /Users/eduardopoleo/.rbenv/versions/2.0.0-p353/lib/ruby/gems/2.0.0/gems/activesupport-4.0.5/lib/active_support/dependencies.rb:229:in `require'
      from /Users/eduardopoleo/.rbenv/versions/2.0.0-p353/lib/ruby/gems/2.0.0/gems/railties-4.0.5/lib/rails/engine.rb:591:in `block (2 levels) in &lt;class:Engine&gt;'
      from /Users/eduardopoleo/.rbenv/versions/2.0.0-p353/lib/ruby/gems/2.0.0/gems/railties-4.0.5/lib/rails/engine.rb:590:in `each'
      from /Users/eduardopoleo/.rbenv/versions/2.0.0-p353/lib/ruby/gems/2.0.0/gems/railties-4.0.5/lib/rails/engine.rb:590:in `block in &lt;class:Engine&gt;'
      from /Users/eduardopoleo/.rbenv/versions/2.0.0-p353/lib/ruby/gems/2.0.0/gems/railties-4.0.5/lib/rails/initializable.rb:30:in `instance_exec'
      from /Users/eduardopoleo/.rbenv/versions/2.0.0-p353/lib/ruby/gems/2.0.0/gems/railties-4.0.5/lib/rails/initializable.rb:30:in `run'
      from /Users/eduardopoleo/.rbenv/versions/2.0.0-p353/lib/ruby/gems/2.0.0/gems/railties-4.0.5/lib/rails/initializable.rb:55:in `block in run_initializers'
      from /Users/eduardopoleo/.rbenv/versions/2.0.0-p353/lib/ruby/2.0.0/tsort.rb:150:in `block in tsort_each'
      from /Users/eduardopoleo/.rbenv/versions/2.0.0-p353/lib/ruby/2.0.0/tsort.rb:183:in `block (2 levels) in each_strongly_connected_component'
      from /Users/eduardopoleo/.rbenv/versions/2.0.0-p353/lib/ruby/2.0.0/tsort.rb:210:in `block (2 levels) in each_strongly_connected_component_from'
      from /Users/eduardopoleo/.rbenv/versions/2.0.0-p353/lib/ruby/2.0.0/tsort.rb:219:in `each_strongly_connected_component_from'
      from /Users/eduardopoleo/.rbenv/versions/2.0.0-p353/lib/ruby/2.0.0/tsort.rb:209:in `block in each_strongly_connected_component_from'
      from /Users/eduardopoleo/.rbenv/versions/2.0.0-p353/lib/ruby/gems/2.0.0/gems/railties-4.0.5/lib/rails/initializable.rb:44:in `each'
      from /Users/eduardopoleo/.rbenv/versions/2.0.0-p353/lib/ruby/gems/2.0.0/gems/railties-4.0.5/lib/rails/initializable.rb:44:in `tsort_each_child'
      from /Users/eduardopoleo/.rbenv/versions/2.0.0-p353/lib/ruby/2.0.0/tsort.rb:203:in `each_strongly_connected_component_from'
      from /Users/eduardopoleo/.rbenv/versions/2.0.0-p353/lib/ruby/2.0.0/tsort.rb:182:in `block in each_strongly_connected_component'
      from /Users/eduardopoleo/.rbenv/versions/2.0.0-p353/lib/ruby/2.0.0/tsort.rb:180:in `each'
      from /Users/eduardopoleo/.rbenv/versions/2.0.0-p353/lib/ruby/2.0.0/tsort.rb:180:in `each_strongly_connected_component'
      from /Users/eduardopoleo/.rbenv/versions/2.0.0-p353/lib/ruby/2.0.0/tsort.rb:148:in `tsort_each'
      from /Users/eduardopoleo/.rbenv/versions/2.0.0-p353/lib/ruby/gems/2.0.0/gems/railties-4.0.5/lib/rails/initializable.rb:54:in `run_initializers'
      from /Users/eduardopoleo/.rbenv/versions/2.0.0-p353/lib/ruby/gems/2.0.0/gems/railties-4.0.5/lib/rails/application.rb:215:in `initialize!'
      from /Users/eduardopoleo/Desktop/rails_projects/first_app/config/environment.rb:5:in `&lt;top (required)&gt;'
      from /Users/eduardopoleo/Desktop/rails_projects/first_app/config.ru:3:in `require'
      from /Users/eduardopoleo/Desktop/rails_projects/first_app/config.ru:3:in `block in &lt;main&gt;'
      from /Users/eduardopoleo/.rbenv/versions/2.0.0-p353/lib/ruby/gems/2.0.0/gems/rack-1.5.2/lib/rack/builder.rb:55:in `instance_eval'
      from /Users/eduardopoleo/.rbenv/versions/2.0.0-p353/lib/ruby/gems/2.0.0/gems/rack-1.5.2/lib/rack/builder.rb:55:in `initialize'
      from /Users/eduardopoleo/Desktop/rails_projects/first_app/config.ru:in `new'
      from /Users/eduardopoleo/Desktop/rails_projects/first_app/config.ru:in `&lt;main&gt;'
      from /Users/eduardopoleo/.rbenv/versions/2.0.0-p353/lib/ruby/gems/2.0.0/gems/rack-1.5.2/lib/rack/builder.rb:49:in `eval'
      from /Users/eduardopoleo/.rbenv/versions/2.0.0-p353/lib/ruby/gems/2.0.0/gems/rack-1.5.2/lib/rack/builder.rb:49:in `new_from_string'
      from /Users/eduardopoleo/.rbenv/versions/2.0.0-p353/lib/ruby/gems/2.0.0/gems/rack-1.5.2/lib/rack/builder.rb:40:in `parse_file'
      from /Users/eduardopoleo/.rbenv/versions/2.0.0-p353/lib/ruby/gems/2.0.0/gems/rack-1.5.2/lib/rack/server.rb:277:in `build_app_and_options_from_config'
      from /Users/eduardopoleo/.rbenv/versions/2.0.0-p353/lib/ruby/gems/2.0.0/gems/rack-1.5.2/lib/rack/server.rb:199:in `app'
      from /Users/eduardopoleo/.rbenv/versions/2.0.0-p353/lib/ruby/gems/2.0.0/gems/railties-4.0.5/lib/rails/commands/server.rb:48:in `app'
      from /Users/eduardopoleo/.rbenv/versions/2.0.0-p353/lib/ruby/gems/2.0.0/gems/rack-1.5.2/lib/rack/server.rb:314:in `wrapped_app'
      from /Users/eduardopoleo/.rbenv/versions/2.0.0-p353/lib/ruby/gems/2.0.0/gems/railties-4.0.5/lib/rails/commands/server.rb:75:in `start'
      from /Users/eduardopoleo/.rbenv/versions/2.0.0-p353/lib/ruby/gems/2.0.0/gems/railties-4.0.5/lib/rails/commands.rb:76:in `block in &lt;top (required)&gt;'
      from /Users/eduardopoleo/.rbenv/versions/2.0.0-p353/lib/ruby/gems/2.0.0/gems/railties-4.0.5/lib/rails/commands.rb:71:in `tap'
      from /Users/eduardopoleo/.rbenv/versions/2.0.0-p353/lib/ruby/gems/2.0.0/gems/railties-4.0.5/lib/rails/commands.rb:71:in `&lt;top (required)&gt;'
      from bin/rails:8:in `require'
      from bin/rails:8:in `&lt;main&gt;'
  </code></pre>