Issue #2137273: Fallback when there is a booking without name.

https://drupal.org/node/2137273

It seems the reporter, for some reason has a booking where the 'name' column in the table is empty. Resulting in an error inside the json generating function for a date range in the availability calendar, leaving a whole date range without events.

The 'name' column should never be empty, but it is not possible to determine what caused this case. This fix avoids leaving a whole date range empty in the availability calendar, handling this cases more nicely.