added bash tab completion for built-in commands (Mac OS/Homebrew)
added bash tab completion for built-in commands (Mac OS/Homebrew)

[finishes #131604695]

Signed-off-by: Alex Melnik <133b34882c9a7536fb0c644d95ec8ca567374456@hpe.com>

cloudfoundry/cli,cloudfoundry/cli,cloudfoundry/cli