Allow prompt-less first-time setup of admin users via ENV var

Set `HOODIE_SETUP_PASSWORD` in the environment before running
`hoodie start` for the first time to use that password for the
Hoodie admin user.

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Merge pull request #177 from hoodiehq/feature/auto-setup

Allow prompt-less first-time setup of admin users via ENV var
block _all_dbs

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This commit was sponsored by Human JavaScript.
Human JavaScript is the best way to learn modern
web application development today, read it now:

http://go.hood.ie/human-javascript
Merge branch 'block-_all_dbs'