add timezone support via query param

Have a look-see @jh-bate 

How it works: before the hash add `?timezone=[timezone-name]` where `timezone-name` is a valid timezone recognized by moment-timezone, only replace any `/`s with `-`. (For example, to view in U.S. Eastern, add `?timezone=US-Eastern` before the hash. You can use their map tool on the [homepage](http://momentjs.com/timezone/) to find out timezone names.

NB: right now the timezone parts have to be capitalized properly as per the names, `?timezone=us-eastern` won't work. (I need to fix the testing for valid timezone name in sundial...)