Fix npm install

npm is unhappy about iced-coffee-script version:

```
npm ERR! notarget No compatible version found: iced-coffee-script@'>=1.7.0 <1.8.0'
npm ERR! notarget Valid install targets:
npm ERR! notarget [..., "1.7.0-a","1.7.1-a", ...]
```

Add a `-` to fix it.