Notification system in frontend

- Heatmap worker now reports progress
- Base for new altitude value
- Phones can be marked active

backend/models/phone/phone.interface.ts

@@ -8,6 +8,7 @@ export interface IPhone extends Document {
     operatingSystem: String,
     architecture: String,
     user: IUser,
+    active: Boolean,
     updatedAt?: Date,
     createdAt?: Date
 }