Make dotfiles compatible with gitpod style dotfiles

Add an install.sh that attempts to determine the OS, install stow and
then call my apply-dotfiles script to use stow.

The old installation process that was based on nix, has been moved to
nix-install.

apply-dotfiles

@@ -1,13 +1,17 @@
-#!/usr/bin/env nix-shell
-#! nix-shell -p stow -i bash
+#!/usr/bin/env bash
 
-stow bash
-stow sh
-stow readline
+apply_dotfile() {
+  directory_to_stow="${1}"
+  stow -D -d "${directory_to_stow}" -t "${HOME}"
+}
 
-stow vim
+apply_dotfile bash
+apply_dotfile sh
+apply_dotfile readline
 
-stow ruby
-stow python
+apply_dotfile vim
 
-stow ssh
+apply_dotfile ruby
+apply_dotfile python
+
+apply_dotfile ssh