For MIFOS771 - CRUD operations on SMS Gateway, plus gateway config test sms

This code allows users to perform CRUD operations on SMS Gateways. After configuring an account with the gateway, the user can persist their gateway name, authToken, url for use when sending SMS messages. Users can also test their gateway configuration with this API. 

Currently, there is a class that handles a web connection to FrontlineSMS. Additional classes will be needed to handle the particular configuration of other providers.