Add extra flag to commands to include sk

[andrewxhill]

If I do a command like

textile account sync all my logs contain sk entries. e.g.

{
    "id": "12D3KooWA3ML7cwqzJ8F4k6R5iR8XBhm238BcibFNEEAJVCuAu5C:QmXisQfoC5LURojE3sKH2MGJWQCeDNWccFUUcVdYwFrn6T,QmR6naokKXXVnxQyTLAHgP1krsE5sWte8BbCqcJqPuCcoW,QmTuyeZhUfT5dikwog5sdfsCfsWH3EqvSqYYx8B4QnUjyq",
    "value": {
        "@type": "/Thread",
        "id": "12D3KooWA3ML7cwqzJ8F4k6R5iR8XBhm238BcibFNEEAJVCuAu5C",
        "key": "textile_photos-shared-1cec80ee-63b2-4ffb-bfc9-34fd9fa479c3",
        "sk": "<exposed>",
        "name": "IPFS Camp 2019",
        "schema": "QmeVa8vUbyjHaYaeki8RZRshsn3JeYGi8QCnLCWXh6euEh",
        "initiator": "P4obBwkeJZvQuB2S4grkFNugfXC1Ab9j6fMW18GKgB3ddMoc",
        "type": "OPEN",
        "sharing": "SHARED",
        "state": "LOADED",
        "head": "QmXisQfoC5LURojE3sKH2MGJWQCeDNWccFUUcVdYwFrn6T,QmR6naokKXXVnxQyTLAHgP1krsE5sWte8BbCqcJqPuCcoW,QmTuyeZhUfT5dikwog5sdfsCfsWH3EqvSqYYx8B4QnUjyq"
    }
}

I can't share my logs with you and if I was doing anything advanced with Textile I guess I'd need to scrub any output containing that.

Could we omit sk fields from log output by default?