Improve/Fix seed script

Seed script fails partway through (this was brought up in #419).

Also, it would be nice if we could add another script or a flag option or what have you for 'quick mode', which woudl auto generate app configs and other metadata and generate some fixed number of database items
if zero categories are created, we cannot allow creation of equipment models, objects, blackout dates, requirements, etc etc, i.e., if we allow creating zero categories in the seed script, we should stick in an

```
else
  puts SOME_ERROR_MESSAGE
  exit
```
to gracefully exit the seed script.