Investigate `failure` crate

[jpeddicord]

askalono uses a lot of Box<Error>. The failure crate has been making a buzz: https://github.com/withoutboats/failure

This is likely a good error management story for askalono. I haven't done any research into actually implementing this; it's likely not too difficult to do.

[davidbarsky]

Steve Klabnik and Ashley Williams made a good point on Twitter. Libraries that use custom derive (like Failure or Structopt) allow people to have write super-declarative code, where it's feasible to define a struct or enum, add an annotation, and do your thing. It's really nice to not worry about imperative builders anymore!

[jpeddicord]

Done in PR #12, thanks!