Deletes unused/broken code for archiving classes and programs

I removed the `archive()` method of a class section, which uses UserBits and should no longer work. It looks like it was written back when it was useful to archive classes and decrease the size of the data tree. We stopped archiving classes around 2012. I also removed the following things, which depended on or were only necessary because of this function:
* the `archive()` method of Program
* the monthly job that we used to run to archive old classes
* the `__init__.py` file of the folder for monthly jobs, which otherwise only contained the above script