fix to save and load schedule properly

The way that the "meta" field config works in the dynamic content is that it is an accessor and not really a field in the table-- so it can store a hash and be manipulated however desired.  What happens is when the content record loads the "config" info is parsed from the data field.  When the content record is written, the "config" info is packaged back into the data field.  We do the same thing here for the scheduling plugin by storing the schedule_info in the schedule field of the table.  The ugly thing about this is that I had to create an accessor for schedule_info in the content model in the concerto repo.  Ideally we could have created that dynamically from this plugin-- but I didn't know how to do that.  In the line above, "schedule" is just a local name and does not correspond to the schedule field in the content table.