feat(daemon) `ipfs daemon --initialized`

With this PR, users can fetch and run ipfs in _one_ command.

```
docker run -d -p 4001:4001 -p 5001:5001 jbenet/go-ipfs daemon --initialized
```

Magic.

nb: needs https://github.com/jbenet/go-datastore/pull/9
i dont think we should import our `errors` package as `errors`. it will be confusing to other golang devs. i think we should be explicit and import it locally as `ierr, ierrors, ipfserr` or something.