Allow selection of multiple contiguous slots for restricted resource types

[johnmckerrell]

In the calendar UI we need to allow the user to select multiple contiguous slots somehow. This should only be allowed for restricted types. The main reason is because room bookings have half hour slots but we want to allow a user to book for a few hours at a time. We can consider setting a maximum number/duration but this isn't vital at this time. Once the slots have been selected and the user decides to move forward the start and end times for the entire span of slots should be passed onto the booking page.

AC:

• I can select multiple slots contiguously
• I can cancel my selection or somehow choose a different set of slots (within the calendar, not cancelling a booking)
• I can go forward to the booking screen and have the time span for my entire selected list of slots be passed on