Add `-j/--json` output for `git-cl`
Add `-j/--json` output for `git-cl`

Useful for the same purposes as the `gcl` wrapper, but easier to parse.
Also adds contents of stdout and stderr.

benizi/dotfiles,benizi/dotfiles,benizi/dotfiles,benizi/dotfiles,benizi/dotfiles,benizi/dotfiles,benizi/dotfiles,benizi/dotfiles