Description of problem:

We would like to provide a user-friendly maintenance mode page during downtime periods. This page should be configurable so that we can state downtime period start and duration, without having to manipulate the page itself. If the configuration file does not exist, something vague is perfectly suitable (e.g. Bugzilla is currently undergoing maintenance). 

The configuration should be through reading a file, or similar. The page MUST NOT access the database! The configuration could be start time in UTC, duration in minutes and perhaps a custom message (in general a standard message will likely be fine)

If the page can display times in a guess of the user's timezone (again, without accessing the database), that might be helpful to the user, but otherwise UTC is fine.