Adds functional producer for SMS - Mobile Commons <-> CGG

- Adds functional producer for Mobile Commons / SMS messaging for US based user signups
- Fixes scope issues for MB_Toolbox class
- Fixes use of MB_Configuration class to gather exchange/queue settings.
It's set a little further up:
https://github.com/DoSomething/mbc-externalApplications-services/blob/f50b8711dda2f6966907ade312c800f5f6653079/mbc-externalApplications-user.php#L27-L33