NPE in audit logging when changing an user's roster

http://www.igniterealtime.org/community/message/172063

The attached patch fixes a NullPointException exception that occurs when editing a roster item. This problem first started occurring in 3.5.0, likely due to the new admin interface. This problem is still present in the latest nightly build. The source of this problem is improper initialization of webManager, probably the result of incorrectly copying and pasting. The comments in the file user-roster-edit.jsp, fixed by this patch, indicate that it was copied from user-roster-delete.jsp file and therefore the comments also need updating.