Add a directory path option when creating a doc.

[kevintech1020]

For now, I can create a doc with a title, but I can't specify the directory. I want the folder to be created if it doesn't exist. File directory check and create feature before creating a doc is helpful.

[taylorwilsdon]

Ah that's a good idea, I believe you can specify the parent ID in files.create() calls so it should be trivial. PR welcome or I'll handle it in the next version!