Update code/controllers/DocumentationViewer.php

BUGFIX: fixed false variable name in DocumentationViewer::set_recursive_submenu()
Update code/controllers/DocumentationViewer.php

BUGFIX: fixed mechanism to get nested page entities when using upper case chars as the first char of a markdown files name or a folders name
Merge pull request #24 from sdiel/patch-1

Ensure comparison is case insensitive.
Merge pull request #23 from sdiel/patch-1

Update code/controllers/DocumentationViewer.php
Fixing functions called statically to be declared as such
Improve default template of DocumentationViewer

class "container" was missing, so a bunch of CSS wasn't being applied.
The layout of the default docsviewer checkout now looks more like the
one on doc.silverstripe.org.
BUG Fixing search not working when no specific versions of docs