Updated DynamicPublishedContent's methods to just proxy calls to the new extension methods so that all of the logic is contained in one place.
Added new GetRootDocuments to the IPublishedContentStore since we need this in order to get the root list of documents for many of these methods.
Fixed an issue with the DynamicNode to IPublishedContent converter.
Fixed many of the failing unit tests.
simplified some of the DynamicPublishedContent methods to accept Func<IPublishedContent> instead of Func<DynamicPublishedContent>, made the IsHelper method private as this shouldn't be exposed.
renamed other objects starting with DynamicDocument to DynamicPublishedContent
the methods in UmbracoHelper so we only have to maintain one set of code. Didn't port over the Wrap methods because
I need feedback on these as to what they do/are supposed to do.
Added the Media methods to UmbracoHelper using the media store stuff.
