shfmt supports spaces, so let's avoid tabs

[DanaLacoste]

What

Changes the default config for the shell script formatter to use tabs rather than spaces

Why

It was explained when shfmt was added to this repo that shfmt uses tabs, but it turns out there was a feature added to shfmt to permit spaces, so this would be a more natural default for .sh files.

I routinely end up having to fix PRs that got tab-ified, so this is a real time saver.

Checklist

• [*] Send RFC email to Braintree developers (via slack)

[ssgelm]

Yes please!

[jcoleman]

I won't pretend to fully understand the vimrc changes here, but I'm very much in favor of the headline change.

[DanaLacoste]

ALE config for sh:
https://github.com/dense-analysis/ale/blob/master/doc/ale-sh.txt#L135

shfmt option which added the -i flag:
mvdan/sh@a441e10

In testing before my PR:

#!/bin/bash
echo "this is a test"
if [[ -e /test ]] ; then
        echo "this line has a tab"
fi

after my PR:

#!/bin/bash
echo "this is a test"
if [[ -e /test ]] ; then
  echo "this line has two spaces"
fi