Add email abstraction layer and sendgrid implementation
Add email test, and use secret credentials
Implmenet device sharing endpoints
Return friendly name of device after sharing transaction has completed
Use device name as email subject, and report device status for /devices endpoint
Only include device in devices list if its SDDL can be parsed
Only store 1 out of 10 sensor samples; send latest sensor data w/ devices request
Hopefully fix too many open files problem
Store control values in sensor_data table
Report control values in devices response
Be sure to close cassandra sessions (this was causing too many files open bug)
Implement device creation