Ported String types to Text

Changed all human-legible String types to Text. Also cleaned up some unnecessary type conversions and removed unused packages.
TBH I think the way we're using IsNsRestletConfig could do with some work. Maybe we could make something that can be used with lenses, like Heist's configuration? (Then again, I had some real problems when trying to work with that, since it wasn't well documented. I'd have to write some decent docs for that.)