R1:e49251ec9804

Improve robustnesss of feed text rendering

Summary:
Couple of minor cleanup things here:

- Pass handles to ApplicationTransactions when rendering their stories; this happened implicitly before but doesn't now.
- Add `?text=1` to do ad-hoc rendering of a story in text mode.
- Make Conduit skip unrenderable stories.
- Fix/modernize some text in the Commit story.

Test Plan: Rendered text versions of stories via Conduit and `?text=1`.

Reviewers: btrahan, chad

Reviewed By: chad

Subscribers: zeeg…