title: mailchimp 3.0 authentication fails
body: <p>Authentication fails for the following, which gets posted to mailchimp using CURL, where API_KEY is defined as a string containing my key.  Similar code used to work just fine for mailchimp v2:</p>
  
  <pre><code>$params = array ('apikey' =&gt; API_KEY,
                   'email_address' =&gt; $email,
                   'status' =&gt; 'pending',
                   'merge_fields' =&gt; array ('fname' =&gt; $first_name,
                                            'lname' =&gt; $last_name
                                           )
                  );
  </code></pre>
  
  <p>The error is:</p>
  
  <pre><code>{"type":"http://kb.mailchimp.com/api/error-docs/401-api-key-missing",
   "title":"API Key Missing",
   "status":401,"detail":
   "Your request did not include an API key.",
   "instance":"(long number)"
  }
  </code></pre>