support multiple globs in host specification

```
It would be nice to be able to use multiple globs in host specifications.

I.e. foo[1-6]vm[1-10] to fan out to the 60 hosts foo1vm1, foo1vm2, foo1vm3, ... 
foo2vm1, foo2vm2, foo2vm3, ... foo6vm8, foo6vm9, foo6vm10.
```

Original issue reported on code.google.com by `brianjmu...@gmail.com` on 17 Apr 2015 at 3:44
