UC-138 Enforce having the right fbAppId or zero.

* Also assume there is only one mapping returned by all load functions
* Simplfy logic based on above
* Rearrange methods to consolidate class vs instance methods
* Rearrange methods to be closer together if they are relted

There is on exception to the last point, 'loadFromDB'.  Moving this to the 'right' place would have made the code changes that also happened harder to see.  Will move this later.