Reduce generated files

[nelson-lojo]

In the generated files, there are some files that don't serve a purpose in some cases (e.g. server.py for ruby autograding) and there are files that end up as part of the generated questions that aren't really needed for PL to render it (e.g. source.py).

There should be an option (or perhaps a sequence of options) that reduce the number of files generated.

For example, a flag that omits the inclusion of the source file or the metadata file in the generated question.

[nelson-lojo]

This issue is exacerbated by the fact that in CS169 generation sources import almost all fields, making the source file basically useless on its own