Add SMS support

Summary:
Provides a working SMS implementation with support for Twilio.

This version doesn't really retry if we get any gruff at all. Future versions should retry.

Test Plan: used bin/sms to send messages and look at them.

Reviewers: chad, epriestley

Reviewed By: epriestley

Subscribers: aurelijus, epriestley, Korvin

Maniphest Tasks: T920

Differential Revision: https://secure.phabricator.com/D8930

externals/twilio-php/docs/usage/rest/queues.rst

@@ -0,0 +1,56 @@
+=============
+Queues
+=============
+
+Create a New Queue
+=====================
+
+To create a new queue, make an HTTP POST request to the Queues resource.
+
+.. code-block:: php
+
+    require('/path/to/twilio-php/Services/Twilio.php');
+
+    $client = new Services_Twilio('AC123', '123');
+    // Default MaxSize is 100. Or change it by adding a parameter, like so
+    $queue = $client->account->queues->create('First Queue', 
+        array('MaxSize' => 10));
+
+    print $queue->sid;
+    print $queue->friendly_name;
+
+Listing Queues
+====================
+
+It's easy to iterate over your list of queues.
+
+.. code-block:: php
+
+    $client = new Services_Twilio('AC123', '123');
+    foreach ($client->account->queues as $queue) {
+        echo $queue->sid;
+    }
+
+Deleting Queues
+====================
+
+.. code-block:: php
+
+    $client = new Services_Twilio('AC123', '123');
+    $queue_sid = 'QQ123';
+    $client->account->queues->delete('QQ123');
+
+Retrieve the Member at the Front of a Queue
+===========================================
+
+The Members class has a method called ``front`` which can be used to retrieve
+the member at the front of the queue.
+
+.. code-block:: php
+
+    $client = new Services_Twilio('AC123', '123');
+    $queue = $client->account->queues->get('QQ123');
+    $firstMember = $queue->members->front();
+    echo $firstMember->position;
+    echo $firstMember->call_sid;
+