Remove autogenerated specs
Add spec for existing sensors to SensorReadingsController spec
Move find_or_create Sensor code to Project
Create Project#sensor()

Finds a project's sensor by its project_index
Fix SensorReading#add_readings

Properly assign a sensor_id
Use Project.find_or_create_sensor
Update spec file
Create SensorReadingQuery and QueryOutput
create spec for project
start creating SensorReadingQuery
make Project#get_sensors
begin implementing #index