Has anyone built an app code to connect their Energy Meter by CurrentCost to Smartthings?
No. But I have built a small Linux/Perl script that’ll read all the device stats from it 
Basically it’s an RFXCom device, but the base unit has a connector port which turns out to be a USB to serial device, so you can plug it in to any handy USB port and read the raw XML.
My current plan involves a Raspberry Pi zero (when I can get my hands on one), a script to read the XML stream and store it, a tiny web server and a small DeviceType that simply reads JSON from a web port
The latter means that I can do the same for my SMA solar inverter:D