Sample template POCOs

[marioarce]

Add sample Sitecore template POCOs deriving from ExtendedItem.

• Disclaimer (TextField: Heading, Description)
• HomePage (ImageField: MetaThumbnail; MultilistField: HeadCssLinks)
• PresentationAssetLink (TextField: Link)
• DictionaryRoot (ItemReferenceField: FallbackDomain)
• Style (TemplateId used in Axes predicates)
• Decorate with [SitecoreTemplate] and [SitecoreField]; template GUIDs marked // fixme

Refs #1