Use delayed_job to Queue Notifications
Remove Usage of Custom JSON Gem

An initial pass at the RPC interface relied on a hacked version of
the JSON Gem, allowing it to return fractional numbers as
BigDecimals instead of Floats, which are prone to precision errors.

An issue (or feature request) has been filed. Until then, a
conversion method has been added to change the Floats to BigDecimals
"by hand".
Refactor TwiML Presentation/Organization

Multiple changes to refactor how TwiML is organized.