Show links to unupgraded dependencies at the end

[avh4]

This changes #5 to show the list of packages you might need to check on at the end. The output looks like this (and with links directly to the issues pages):

SUCCESS! Your project's dependencies and code have been upgraded.
However, your project may not yet compile due to API changes in your
dependencies.

See https://github.com/elm-lang/elm-platform/blob/master/upgrade-docs/0.18.md
and the documentation for your dependencies for more information.

WARNING! Several of your dependencies have not yet been upgraded to
support Elm 0.18. You can create an issue to request the packages be
upgraded here:
  - https://github.com/Fresheyeball/elm-tuple-extra/issues
  - https://github.com/NoRedInk/elm-rails/issues
  - https://github.com/NoRedInk/elm-simple-fuzzy/issues
  - https://github.com/NoRedInk/elm-string-extra/issues
  - https://github.com/NoRedInk/nri-elm-css/issues
  - https://github.com/eeue56/elm-all-dict/issues
  - https://github.com/eeue56/elm-default-dict/issues
  - https://github.com/jinjor/elm-diff/issues
  - https://github.com/mdgriffith/elm-style-animation/issues
  - https://github.com/mgold/elm-date-format/issues
  - https://github.com/rluiten/elm-date-extra/issues
  - https://github.com/rluiten/elm-text-search/issues
  - https://github.com/rtfeldman/elm-validate/issues
  - https://github.com/shmookey/cmd-extra/issues
  - https://github.com/thebritican/elm-autocomplete/issues
  - https://github.com/wernerdegroot/listzipper/issues

[avh4]

@eeue56 ^^

[eeue56]

Several -> give exact count

[avh4]

Done!

[eeue56]

Fwiw, we could also automate making 0.18 upgrade PRs

[avh4]

oh making the PRs... Hmm.. That's a cool idea! I think if we wanted to automate the PRs, it would be better to separately just go through all the published packages and create the PRs (as an independent, one-time script), and not have elm-upgrade to that, since so many people will be running it.

Also, I didn't want to automate issue creation because most likely there will already be an issue created, and I don't want all package maintainers to get a bunch of duplicate issue reports.

[eeue56]

Yep, that's what I did for 0.16. It was a bit trickier than because some things just couldn't be done by hand