Add SMS feature/use Twillio?

Aliza's talk at CE Launchpad helped us realize how many people in the city rely solely on their smart phones and SMS, and these are important features to include in an app. Task: investigate twillio as an API for sending/saving the info as a text.

No files, tests, or entry points are named. Start by defining the SMS use cases and reviewing whether the Twilio API can send and save the required information. Done means the integration approach and scope are documented clearly enough to implement.

Written by the indexing model from the issue text.