Adding customization javascript, css, example

The following files are involved:
	new file:   ../../css/osgcustomize.css
	new file:   ../../js/URI.js
	new file:   ../../js/jquery.ba-replacetext.min.js
	new file:   ../../js/osgcustomize.js
	modified:   06-Stash.md

06-Stash.md shows how to use:
<!-- Add these 2 lines to any page you want to be customizable.
  -- The content of the div is JSON to configure the customizer.
  -- If you add "foo": ["Foo bar:", null] to the JSON, then "{foo}"
  -- will be substituted in the document and a "Foo bar" input will
  -- be created in the control box.
  --
  -- If any element in your document has id "osgcustomize-activate",
  -- it will trigger the control panel. Otherwise osgcustomize will
  -- draw this button for you. -->
<div id="osgcustomize" class="hidden">{"username": ["Username", null]}</div>
<script src="/general/js/osgcustomize.js"></script>

...

Here's where this example links to the control button:
You may
<a id="osgcustomize-activate" href="#">customize this tutorial</a>
for your personal details, if you wish.