Revert "Fixed pylint problem with page_text field."

This reverts commit 44a78be79e0e6b072eab01c26e7cb6fd1307c1f2.
Revert "Added page_text field that shows text on Admin ChangeList pages."

This reverts commit 6739b6b73c4122dbc0f973e99e2af3c710a59139.
Revert "Cleaned up the ChallengeSettings and docstrings."

This reverts commit 06bf78fa92580d63201610b93d93cce86141bd0a.