User Selectable Timezones

[cycomachead]

We're almost to the point of making this easy, but still annoying:

• add a query param to schedule routes to override a timezone
• full calendar presenter can convert dates
• the initial request should respect a user timezone setting
• We can use inyourtz function to convert other displays pretty easily. can the block accept a converted_tz option for display? hmm.

[cycomachead]

Fixed with #257