Token expiration functionality

- [x] Log the user out after X time of inactivity
- [x] Auth tokens should be expired by system
This isn't very clear.

Would it be something like this?:
```
MINUTE = 60
HOUR = 60 * MINUTE
DAY = 24 * HOUR
AUTH_TOKEN_MAX_AGE = 7 * DAY
AUTH_TOKEN_MAX_INACTIVITY = 17 * HOUR
```