Changed IPublishedContentStore and IPublishedMediaStore back to internal as we don't need to expose these yet. Instead have added

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.

src/Umbraco.Tests/StringExtensionsTests.cs

@@ -2,7 +2,6 @@
 using System.Collections.Generic;
 using System.Security;
 using System.Text;
-using System.Web.Mvc;
 using NUnit.Framework;
 using Umbraco.Core;