No peer answers displayed in Step 2

[kitsook]

The change 29f7dbc persists peer answers shown to a student.

However, if the student completed Step 1 before ubcpi is upgraded to 29f7dbc, no peer answer will be displayed in Step 2 after the upgrade as there was no peer answer persisted.

Need to add logic to get_persisted_data in ubcpi.py. If there is no persisted peer answers, generate new ones on the fly to simulate behavior of the old versions.