~/.emacs.d: use `go fmt` automatically

.emacs.d/init.el

(add-to-list 'package-archives '("marmalade" . "http://marmalade-repo.org/packages/"))
(add-to-list 'package-archives '("melpa" . "http://melpa.org/packages/"))
(add-hook 'before-save-hook #'gofmt-before-save)
(add-to-list 'auto-mode-alist '("\\.edn\\'" . clojure-mode))
(add-hook 'clojure-mode-hook 'paredit-mode)