make package fails with BSD sed

Specifically, this occurred on OS X.

```
sed -i 's/.\/admin/\/opt\/influxdb\/current\/admin/g' build/config.toml
sed: 1: "build/config.toml": undefined label 'uild/config.toml'
```

See: http://mpdaugherty.wordpress.com/2010/05/27/difference-with-sed-in-place-editing-on-mac-os-x-vs-linux/