MOTECH-1172 Support IVR-Verboice interoperability

Support storing username and password credentials with IVR configs. Provide
Verboice-specific call statuses. Extract JSON data from the response
that results from placing the outgoing call HTTP request, and place data
as parameters on the initial CDR. Provide a lookup for searching by both provider
id and call status (to support finding the initial CDR for a single call).

Change-Id: If1a3edd209c1b0baddf62f907d13ad686593f1ae
Merge "MOTECH-1172 Support IVR-Verboice interoperability"