Allow monomorphism restriction
More explicit imports instead of qualified ones

This makes the imports list more complicated but I think improves the
readability of the code.
Use `text` for rendering HTML

Aside of being more efficient, this should save us from some locale
support pain.

This incurs in an extra dependency, although it was already used
transitively by `blaze-html`.
Drop `reducers` dependency

`tasty-0.8` provides Traversal.