Sets up a filter to determine the log level for a given response.
For each HTTP response this will invoke response_filter to determine how much (if any) of
that response to log. (If you do not set a response filter, this will just always log responses at the
level passed to Logger.)
| this |
a Logger |
| response_filter |
the callback for response debugging |
| destroy |
a DestroyNotify to free |
| filter_data |
data to pass to the callback |