Add Applicative and Functor support when we publish Algebird with it.

[johnynek]

Execution has a more efficient Applicative.join than using flatMap. When we publish the next version we should override join with Execution.zip.

Also, TypedPipe is a Functor, but also Applicative (if it is useful). Applicative comes from cross. It is a bit hard to imagine, an the moment, a uses example of generalizing Applicative on TypedPipe, but Functor is pretty obvious.