Fix actions page when no user is available.

Fixes https://github.com/jsha/blocktogether/issues/119
Resurrect dead workers.
Statically serve favicon.
Update first-time setup instructions.
Replace cookieSecret with __COOKIE_SECRET__
Return a 404 rather than 500 for nonexistent block lists.
Disable block updating from stream.js. Enable it from my-blocks.
Version 1.0.3
Merge branch 'master' into smarter-update-blocks

Conflicts:
	blocktogether.js