Allow nesting pages under other pages

Completed Edit me

A user can nest any page under another page, creating a parent-child relationship

User Story

As a PRACTICAL ™ Documentation System User, I want to be able to nest a page directly under any other page, and have the “parent” page automatically show up in the navigation as-if it were a folder, containing all of it’s “children” pages.

Acceptance Criteria

Scenario 1
- Given that I have some page “A.html” and another page “B.html” …
  
  and both files exist in the “my_product” folder under “pages”
- When I use the “folderitems” element in the the sidebar yaml file for my product as follows:
```
- title: This is Page A
  url: /pages/my_product/A.html
  output: web, pdf
  folderitems:
  - title: This is Page B
    url: /pages/my_product/B.html
    output: web, pdf
```
- Then the Page “B.html” appears as a nested link under Page “A.html”
Scenario 2
- Given that I have some page “A.html” and another page “B.html” …
  
  and page “A.html” exist in the “my_product” folder under “pages”
  
  but page “B.html” exist in the “my_product/a_children” folder under “pages”
- When I use the “folderitems” element in the the sidebar yaml file for my product as follows:
```
- title: This is Page A
  url: /pages/my_product/A.html
  output: web, pdf
  folderitems:
  - title: This is Page B
    url: /pages/my_product/a_children/B.html
    output: web, pdf
```
- Then the Page “B.html” appears as a nested link under Page “A.html”, just as before. i.e., it looks no different either way

Implementation

To implement this, the following items were changed in the Jekyll Documentation Template:

Eliminate the silly "Entries" list and associated "For each" template that allows definition of more than one navbar at a time. It's broken anyway.
Update the sidebar template to determine if this is a folder by checking for nested folder items.
Eliminate the "Folders" tag in the sidebar yaml.
Deal with the problem of folders not being 'Active' (may resolve itself... we'll see)