.osx: Add possible values for AppleShowScrollBars

Ref. #170.
Update shebangs

If the user installs a custom Bash build, why not use it?

Ref. #196 and #198.
README: Add author field
.functions: Add `targz`

`targz some-directory` creates `some-directory.tar.gz`, where compression is handled by either `zopfli` (if available) or `gzip`.
.functions: Avoid `rm` error message in `targz` when `gzip` is used
Merge branch 'master' of github.com:mathiasbynens/dotfiles

* 'master' of github.com:mathiasbynens/dotfiles:
  .functions: Avoid `rm` error message in `targz` when `gzip` is used
  .functions: Add `targz`
  README: Add author field
  Update shebangs
  .osx: Add possible values for AppleShowScrollBars