title: Missing port when starting Rails with Foreman
body: <p>I am new to RoR and I am trying to install specific project. My OS is Ubuntu 14.04 and I trying to run the project from terminal. I have already installed all needed gems following project's specifications.</p>
  
  <p><strong>Issue</strong></p>
  
  <p>When I run this command which is trying to run the project</p>
  
  <pre><code>foreman start -f Procfile.dev
  </code></pre>
  
  <p>It gives me the following error</p>
  
  <pre><code>17:01:33 web.1    | started with pid 4538
  17:01:33 worker.1 | started with pid 4540
  17:01:34 web.1    | /home/user/.rvm/gems/ruby-2.1.3/gems/railties-4.0.9/lib/rails/commands/server.rb:33:in `parse!': missing argument: --port (OptionParser::MissingArgument)
  17:01:34 web.1    |     from /home/user/.rvm/gems/ruby-2.1.3/gems/rack-1.5.2/lib/rack/server.rb:293:in `parse_options'
  17:01:34 web.1    |     from /home/user/.rvm/gems/ruby-2.1.3/gems/rack-1.5.2/lib/rack/server.rb:184:in `options'
  17:01:34 web.1    |     from /home/user/.rvm/gems/ruby-2.1.3/gems/railties-4.0.9/lib/rails/commands/server.rb:58:in `set_environment'
  17:01:34 web.1    |     from /home/user/.rvm/gems/ruby-2.1.3/gems/railties-4.0.9/lib/rails/commands/server.rb:42:in `initialize'
  17:01:34 web.1    |     from /home/user/.rvm/gems/ruby-2.1.3/gems/railties-4.0.9/lib/rails/commands.rb:71:in `new'
  17:01:34 web.1    |     from /home/user/.rvm/gems/ruby-2.1.3/gems/railties-4.0.9/lib/rails/commands.rb:71:in `&lt;top (required)&gt;'
  17:01:34 web.1    |     from bin/rails:4:in `require'
  17:01:34 web.1    |     from bin/rails:4:in `&lt;main&gt;'
  17:01:34 web.1    | exited with code 1
  17:01:34 system   | sending SIGTERM to all processes
  17:01:34 worker.1 | terminated by SIGTERM
  </code></pre>
  
  <p>This is what I have in Procfile.dev:</p>
  
  <pre><code>web: bundle exec rails s --port $DEV_PORT
  worker: bundle exec rake jobs:work
  # exec: lt --port $DEV_PORT --subdomain $SUBDOMAIN
  </code></pre>
  
  <p>Could you please tell me how to solve this problem?</p>