an UmbracoHelper property to the PluginController class which will expose any methods needed by devs to retreive media or content.
Have updated UmbracoHelper with loads of new helpful methods and moved the Wrap methods to HtmlHelper extensions because this is purely to
do with rendering html (have written unit tests for it too).
Updated some 'library' methods to proxy calls to UmbracoHelper so we only have to maintain one set of code.
Added a convenience property to UmbracoContext to return the current NiceUrlProvider so you don't have to go through the RoutingContext to get it.
Adds UmbracoHelper as a property to the RenderViewPage for MVC. Tested rendering Xslt and Razor macros with and
without parameters and works well.
Next we need to get the RTE rendering with macros embedded in MVC.
