Add a two-tier data quota system

Issue: Currently, there's no good way for users to account for having a separate primary quota effective some hours, and a secondary data quota or unmetered data effective during the remaining hours, from within the router's settings.

Background: Some ISPs have two-tier data quotas, saying you get this primary data quota to use during these hours, and either this secondary quota to use during these other others (e.g., you get 20 GB/mo to use from 0800-0200, and 50 GB/mo, counted separately, to use from 0200-0800), or unmetered data to use dring these other hours (e.g., 25 GB/mo from 0600-0300, and then unmetered data from 0300-0600).

Proposed solution: On the Traffic Meter setting page, have users specify whether they have a data quota, and, if so, add a setting to specify whether it's a one- or two-tier quota system. If two, the effective hours for each, and whether the second tier is metered or unmetered, and, if metered, what the secodary quota is.