extract cookie as well as token for slack auth

[jackellenberger]

Why

Welp, Slack is cracking down. The days of using tokens for whatever the heck you want are over, now we need cookies too. I used to love cookies, ya know?

Anyway, as part of the response to jackellenberger/emojme#60, we need an easy way to extract both a slack token and its cooperative cookie, which is wisely unfortunately, HttpOnly. This means we can't just grab it in javascript, you need a them on the inside... a them like... google chrome. So here this extension is, requesting more permissions to do more seemingly nefarious but really quite silly things.

What

The actual change here (in addition to adding cookies permissions, is to update the Get Slack Token button to be a Get Slack Token and Cookie button. Clicking it will return (and copy to your clipboard) a jsonblob containing the slack subdomain, token, and cookie.

What's next

Update emojme to accept these auth blobs so emoji shenanigans remains a bada bing bada boom type operation, nice and easy. :promoves: