Add additional metrics to devices

[420goonsquad420]

Users request multiple new metrics:

• [x] Airflow
• [ ] Cleanability
• [ ] Mouthpiece material(s)
• [x] Battery replaceability
• [ ] Warranty / customer support
• [ ] Temperature control
• [x] Flavour (this will be very subjective)

[420goonsquad420]

• [ ] Convection/conduction should be a fraction rather than "conduction", "convection", "hybrid"