Add ability to transduce values collected via clojure.core.async/into
This is a trivial change that allows a transducer to be provided as the first argument to clojure.core.async/into. This feels like a common use case ... transforming values and conj'ing them into a collection, as with (transduce xform conj  ch).
Patch 3 doesn't include the change to CONTRIBUTING.md
This fixes two typos I, of course, didn't notice until after submitting.