Property booking structures

When a booking is made, we also need to tie the booking to a property. The PropBooking structure includes the property key (for later reference), as well as Name and Location, both of which were previously defined. Here is the structure:

PropBooking = {
    "propertyKey"     : <string>,
    "propertyName"    : <Name>,
    "propertyAddr"    : <Location>
    "propertyContact" : <Contact>
}

In addition, when a booking is made, we need to identify the roomType that was booked, as well as the quantity of that room type the customer wishes to reserve. 

By including the price property, we alleviate the need to perform an additional booking when referencing booking information. Note that we include the roomType field, drawn from Common.roomType, as well as the roomTypeKey field, drawn from RoomType.roomTypeKey.  The reason why we include both is that roomType is for display...