Tool to show differences between two versions of a package

In short, copy elm-package diff. For example:

$ elm-package diff evancz/elm-markdown 1.0.0 1.1.0

Comparing evancz/elm-markdown 1.0.0 to 1.1.0...
This is a MINOR change.

------ Changes to module Markdown - MINOR ------

    Added:
        type alias Options =
            { githubFlavored : Maybe { tables : Bool,
                                       breaks : Bool
                                     },
              sanitize : Bool,
              smartypants : Bool
            }
        defaultOptions : Options
        toElementWith : Options -> String -> Element
        toHtmlWith : Options -> String -> Html

Source: http://elm-lang.org/blog/announce/0.14#better-build-tools

I wonder if it might work better for us to implement this inside the Pursuit web app, though.

Use the elm-package diff example as the behavioral reference, then review the Pursuit web app's existing package and version-handling entry points. Resolve whether the comparison belongs in the web app or as a separate tool, and consider the work complete when two package versions produce a useful change classification and API difference report.