[rbdemo] Create media/images/ after resetting media files.

Review Request #5877 — Created May 25, 2014 and submitted — Latest diff uploaded




reset-demo was wiping the media directory and copying over the new
files, but these didn't necessarily have an images/ directory. This
meant that the directory wouldn't be created, and the Manual Updates
would kick in.

We now explicitly create the required directories if they don't exist.

Tested on demo.reviewboard.org as well, where this happened, causing an
error. Saw that it was fixed.