Support for new token system in Discourse

**WARNING:** I have not tested this, and it's probably very very very very very very very very broken.

Review the changes very carefully, they may not even run.  I haven't tried yet.

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Companion PR to hummingbird-me/hummingbird#322

The auth_token field is set to "auth_token|user_id" and then we query using a LIKE with a wildcard based on which half we care about.  It's hacky, but it's there to support Tenpenchii users during the migration, after which point we can drop the part before the pipe.

If we decide it's just easier to not bother with supporting them during the migration and YOLO-ing it, I can tear out that hack and we can go directly to auth_token-as-user_id

**Known Issues:**
 * Probably breaks with old values in the auth_token field.  I should fix that.