Fixed a small bug in the UCLA task creation script

I had erroneously assumed that all questions had paths in the form "/data/\<question_id\>". This of course meant that questions within question groups were not handled properly. These changes remove that assumption and fix the issue.

@dannyroberts or anyone
Could this silently overwrite questions with matching ids? For context, it is valid to have an xform with two questions having the following paths:

```
/data/question
/data/group/question
```