Extend equipment model availability calendar length to 6 months

[orenyk]

From UP(Undergraduate Productions):

Cannot use calendar to scroll more than a month into the future to browse day-by-day availability. We would like to be able to scroll 5 months in advance.

This might slow down this page a bit since it will have to pull in more Reservations for availability calculations but since the calendar scrolling is completely client-side, I can't see a reason not to do this.