left-over code tweaks from cross-merge

* #1148  `parent` and `parents` were changed to `parent_id` and `ancestor_ids`, but a new piece of code was not changed before merge.  Change it here.
* requests module is annoying with logging.  Turn it off.
* #1149 KA exposes exercises that are not "live".  Don't include them in our topic tree (10 total)

This is tested and ready to go. @jamalex if you have a minute, cool.  If not, fine to merge.  This should be put in ASAP.