unwrap clump results with clump.get convenience method

@fwbrasil interested in your opinions around naming conventions with `run` vs `get`. The get in this case was inspired by `option.get`. But scala seems inconsistent about what `get` means because for a map, a `get` returns an `Option` while apply is the strict one that may fail.
I tried replacing this with `def get(implicit default: T): Future[T] = run.map(_.getOrElse(default))` and putting a `implicit val defaultList = Nil` in the Clump companion object but it didn't work. My knowledge of implicits is too crap :). I am not sure how to reconcile implicits with generics