Switching to JSON lookup of library hours

- Removing unused calls to isOpen() function

- Removing calls to getHoursToday in page-main-locations and
content-location (but have to keep in page-study-spaces for now)

- Adding buildHours to core.js, and hours.json

- Adding data-location-hours attribute that buildHours is looking for.
The key is currently the_title, but can be switched easily enough in
core.js and hours.json