pat-calendar: Time zone is not persisted in storage

[reinhardt]

When using pat-calendar with store other than "none", view and date are persisted in the storage, but time zone isn't, i.e. when I select a time zone and reload the page I go back to the default zone.

I'm referring to the new pat-calendar in the slc branch,

https://github.com/Patternslib/Patterns/blob/slc/src/pat/calendar.js#L282