Base: Change ServiceContainer abstract

Also create AbstractSingleton class as its parent.
Test: Use ServiceContainer in root db relate testcase
Config: Make class Config implements ArrayAccess

So it can use instance of Config class as array style.
Base: Combine ServiceContainer together with Dependency Inject

This is best practice I can thought now, see comment in class ServiceContainer
for more infomation.
Html: New class DocumentView and migrate class/doc-markdown.php

To: Fwlib\Html\TextDocument\Markdown
Html: Add raw view and output of html title
doc: Use new DocumentView class as renderer

Also made necessary change to DocumentView class, and add a new css file.
doc: Change file to .md ext, as they are Markdown syntax

Some useless document removed.