Do not split a host over multiple lines

When the host table has two lines and a hostname is long, it can happen
that it's split over multiple lines. By using a non-breaking space this
shouldn't happen. The problem is this:

![line](https://f.cloud.github.com/assets/155810/335679/8af0796a-9c93-11e2-84d8-65d9e47672e5.png)

Note that it's untested and just an idea how it could be solved. Maybe the optimal solution would be to not truncate at all in ruby, but just use text-overflow: ellipsis (http://quirksmode.org/css/user-interface/textoverflow.html), but I'll leave that for someone else :).