Query limit to be configurable

[praiskup]

Red Hat Bugzilla applied policy that anonymous queries can get at most 20 lines in the API output, and authenticated queries up to 1000.

So it is probably a good idea to "push" Red Hat maintainers to the authentication (interactive=True) a little bit more and set some reasonable default limit (limit=1000), otherwise the output will be very limited (and there's a risk that user misses some bugs thinking that the output is complete).

Both of those options can be changed in $HOME/.bugzrc.