Fix #33 (implement smart labels as `categorize` action and remove doc…

[grimm26]

…umentation about CATEGORY_* labels that do not place emails into the tab categories.

[mesozoic]

Thanks for the bug report and the branch! I'm sorry for the delayed response.

So either this is a change in behavior on Gmail's side, or this actually never worked in the XML import and has only ever worked through the API. (The CATEGORY_* labels do work via API, at least for my own Gmail accounts.)

Maybe you could help me narrow this down a bit more, so we can write some tests to ensure proper behavior?

1. If you use the --sync flag instead of the XML upload, do you find that the existing code works for creating category-based filters? If not, then my own Gmail account might have some legacy behavior that others don't.
2. Have you tested your branch using the --sync flag? The filters.create API only supports adding or removing labels, so I suspect this might break with the branch as-is.

[grimm26]

@mesozoic I think this never worked on the XML side and only via API. I haven't been able to test with --sync because I can't get the google authentication to work.