commands: Support config from ENV
authorBjørn Erik Pedersen <bjorn.erik.pedersen@gmail.com>
Mon, 18 Apr 2016 16:37:32 +0000 (18:37 +0200)
committerBjørn Erik Pedersen <bjorn.erik.pedersen@gmail.com>
Mon, 18 Apr 2016 16:45:37 +0000 (18:45 +0200)
commitb7fd410245ed47a46176735ddc1f292a03bb51fe
treef3231b6951fca6df5793e05346b0fefd936f23cf
parent0743c76795d4a652dea1b9ac9995b2710573457b
commands: Support config from ENV

So

```bash
env HUGO_TITLE="Some Title" hugo server
```

Will change the `title`.

Fixes #2090
commands/hugo.go