Create migrate to remove authors table

[meltedspork]

We are using Auth0's user database so there are no longer necessary for this.

CC: @kratsg

[meltedspork]

Are we removing whole table of authors ? @kratsg

[kratsg]

We are. Need to update IDs everywhere to use the right one from auth0 -- but some testing is required, etc...

[meltedspork]

i am thinking to keep this PR small.

first PR is to remove and second PR is to add from auth0

what can we take from auth0 in replace for?

[kratsg]

auth0 provides a user id. But you should look at what's in the tokens they give us :)

[meltedspork]

this is what we want to store? (not all of it of course) I am assuming - email, email_verfiied, family_name, given_name, groups, roles, and locale?

    "profile": {
        "email": "j*********@****.com",
        "email_verified": true,
        "family_name": "Salerno",
        "gender": "male",
        "given_name": "Jason",
        "https://api.signsfive.com/groups": [],
        "https://api.signsfive.com/roles": [],
        "locale": "en-US",
        "name": "Jason Salerno",
        "nickname": "jms******",
        "picture": "https://scontent.xx.fbcdn.net/v/t1.0-1/p50x50/path-to-my-fb-profile-pic",
        "sub": "facebook|0987654321",
        "updated_at": "2018-02-11T23:39:11.527Z"
    }
}```

[kratsg]

Nope, we only need to store sub: facebook|0987654321 in your case. It specifies the main log-in authenticator provider and the ID for that. It's unique to everyone who logs in, in any way. Everything else we can ping auth0 for if we need the extra information. The access token provided to the API will contain the permissions. So no extra look up needed.

[kratsg]

See https://tools.ietf.org/html/rfc7519#section-4.1.2 for details.