Add 'Current Status' formatter

Hi Guys,

Here's a patch to add the current status (open / closed) to the office hours. It is currently using the timezone of the website, but I will be adding a feature to use the timezone from a tzfield.

Please keep in mind this is essentially a re-write of the display formatter and adds some more themeing options. Previous theme functions for the display formatter should still work, but would need to be re-written to take advantage of the new processing in office_hours_field_formatter_view().