The CommitListField now renders change description entries for the field

more similarily to its regular field view. Previously, it would just

show all old commits as removed and all new commits as added, but now it

performs a history diff between the old and new commits and renders that

instead.
The new template supports rendering commit modifications, however

commit_utils.diff_histories presently cannot generate history diffs

that contain modifications (only additions, deletions, and unmodified

entries).

Ran unit tests.