title: "rails server" on existing working application not starting
body: <p>I'm happily configuring my new laptop to work on my already existing projects. 
  I copied the folder of an application and all its subfolders, and now have it in the new laptop.
  It seems I cannot start the server by typing <code>rails server</code> command at the root of the project.
  I tried to create a new project and start it and it works just fine, so I really have no idea of what to do. Rails versions are the same and identical <code>Gemfile</code>.
  This is the result of the <code>rails server</code> command:</p>
  
  <pre><code>Usage:
    rails new APP_PATH [options]
  
  Options:
    -r, [--ruby=PATH]              # Path to the Ruby binary of your choice
                               # Default: /home/toni/.rvm/rubies/ruby-1.9.3-p374/bin/ruby
    -b, [--builder=BUILDER]        # Path to a application builder (can be a filesystem   path or URL)
    -m, [--template=TEMPLATE]      # Path to an application template (can be a filesystem path or URL)
    [--skip-gemfile]           # Don't create a Gemfile
    [--skip-bundle]            # Don't run bundle install
    -G, [--skip-git]               # Skip Git ignores and keeps
    -O, [--skip-active-record]     # Skip Active Record files
  ETC...
  </code></pre>
  
  <p>thanks!</p>