Fig 'restart: always'

Feature isn't yet supported by any of the released versions of Fig. Fig must be installed from the repository...

```bash
git clone git@github.com:docker/fig.git
cd fig
./script/build-linux # ./scripts/build-osx
sudo cp ./dist/fig-Linux-x86_64 /usr/local/bin/fig
sudo chmod +x /usr/local/bin/fig
```