Fix undeclared instance var in DocController
Extend authorization checks to related tables

Fixes #31

Extend authorization checks to tables whose data is imported or
otherwise read as part of this table setting.  These include:
- tables that provide the source of possible values for a field
- tables from which one is importing data
- tables from which one is initializing data

Provide more detail on authorization errors when exception reporting
is turned on (development and test environment, for example).