Elm Platform (Install) 0.19.0

A bundle of all Elm tools, usable through the elm executable.

This bundles together a bunch of projects that make it nice to use Elm: [`elm-compiler`](https://github.com/elm-lang/elm-compiler), [`elm-make`](https://github.com/elm-lang/elm-make), [`elm-reactor`](https://github.com/elm-lang/elm-reactor), [`elm-repl`](https://github.com/elm-lang/elm-repl), and [`elm-package`](https://github.com/elm-lang/elm-package).