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

Author: bobtrahan

bin/sms

@@ -0,0 +1 @@
+../scripts/sms/manage_sms.php

externals/twilio-php/AUTHORS.md

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+Authors
+=======
+
+A huge thanks to all of our contributors:
+
+
+- =noloh 
+- Adam Ballai 
+- Alex Chan 
+- Alex Rowley 
+- Brett Gerry 
+- Bulat Shakirzyanov 
+- Chris Barr 
+- D Keith Casey Jr 
+- D. Keith Casey, Jr. 
+- Doug Black 
+- John Britton 
+- Jordi Boggiano 
+- Keith Casey 
+- Kevin Burke 
+- Kyle 
+- Kyle Conroy 
+- Luke Waite 
+- Neuman 
+- Neuman Vong 
+- Peter Meth 
+- Ryan Brideau 
+- Sam Kimbrel 
+- Shawn Parker 
+- Stuart Langley 
+- Taichiro Yoshida 
+- Trenton McManus 
+- aaronfoss 
+- sashalaundy 
+- till