all calles in RazorLibraryCore for Wrap to UmbracoHelper. Fixed up the HtmlTagWrapper classes so they have immutable properties and replaced
public fields with Properties.
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.
