TypeError when filtering on certain report sections

[pbourgel]

When filtering on values like the return code for the experiment and control request in the http_requests tests, GenerateFilteredEntryList raises a TypeError on line 335 in probix_helpers.py. Looks like there's two cases where this messes up:

1. ['report'] or ['requests']
2. 0['response'] or 0['code']

I'm going to have to dive into the data structure on this one.