title: Rewrite rule to handle url exception
body: <p>I have an app that serves many sites and I am using Apache mod-rewrite to map the 
  url's like this</p>
  
  <pre><code>http://site1.net/controller
  http://site2.net/controller2/another_view
  http://site3.net/
  http://special_case.net/
  </code></pre>
  
  <p>maps to:</p>
  
  <pre><code>index.php?url=http://site1.net/controller
  index.php?url=http://site2.net/controller2/another_view
  index.php?url=http://site3.net/
  index.php?url=http://special_case.net/hub
  </code></pre>
  
  <p>My rewrite rules are:</p>
  
  <pre><code>RewriteEngine On
  RewriteCond %{REQUEST_FILENAME} !-f
  RewriteCond %{REQUEST_FILENAME} !-d
  RewriteRule ^(.*)$ index.php?url=$1 [QSA,L]
  </code></pre>
  
  <p>Which handles all the cases except the special last case, where I need to force 
  the use of a controller called "hub" when handling a specific domain. I collaborate with others on this project which means I can't do anything about the routing once the index file is called.</p>
  
  <p>Can someone fix my rules so that all the above cases resolve?</p>