Obsoletes umbraco.presentation.cache with new Umbraco.Core.CacheRefreshersResolver

Have removed ResolverBase as we cannot rely on manually setting the current singleton object since applications outside of the standard umbraco web application
might be using these singletons and would expect they already be setup. Have changed all current resolvers to manage their
own singleton instances and sealed them.

src/Umbraco.Core/Resolving/SingleObjectResolverBase.cs

@@ -5,14 +5,12 @@ namespace Umbraco.Core.Resolving
 	/// <summary>
 	/// A Resolver to return and set a Single registered object.
 	/// </summary>
-	/// <typeparam name="TResolver"></typeparam>
 	/// <typeparam name="TResolved"></typeparam>
 	/// <remarks>
 	/// Used for 'singly' registered objects. An example is like the MVC Controller Factory, only one exists application wide and it can
 	/// be get/set.
 	/// </remarks>
-	internal abstract class SingleObjectResolverBase<TResolver, TResolved> : ResolverBase<TResolver> 
-		where TResolver : class 
+	internal abstract class SingleObjectResolverBase<TResolved>
 		where TResolved : class
 	{
 		TResolved _resolved;