Generate HTTP endpoints for environment sensors

- Move update request sanity checks to new method in handlers/util.go
- Change EnvironmentSensor.Value type because ParseFloat returns float64

types/v14.go

@@ -41,11 +41,12 @@ type SpaceAPIResponseV14 struct {
 }
 
 type EnvironmentSensor struct {
-	Value       float32 `json:"value"`
+	Value       float64 `json:"value"`
 	Unit        string  `json:"unit"`
 	Location    string  `json:"location"`
 	Name        string  `json:"name"`
 	Description string  `json:"description"`
+	LastChange  int64   `json:"lastchange"`
 }
 
 type PersistentStateV14 struct {