Change Request: Add configuration fields for time restrictions

[kfreezen]

Time restrictions requires three new fields in the configuration file.

TBD: Set this on users+groups, or just users?

IsTimeRestrictionEnabled

This is a boolean which the application uses to figure out whether it should pay attention to any of the rest of the time restriction settings.

UserTimezone

This is an tz database ID (e.g. America/New_York). This one will require a backing reference table for a select box in order to allow the user easier selection of his timezone.

TimeRestrictionRange

This is a string in the format "00:00-23:59". Note that the client does not support AM/PM time.