Add term as a folder.

[wznmickey]

Do https://github.com/BoYanZh/Canvas-Syncer/issues/52

[BoYanZh]

Why not just use a separate config file for each term?

[wznmickey]

Some courses like undergraduate are not in the same term as regular courses. So the user may need to switch config files and rerun the script many times to download new files. The work of user will increase. Besides, the config file in hidden in the package folder, so some users may not find the place.