Changed PluginResolverType to PluginManager. Reinstated Resolution and ResolverBase<T> since

this gives us more control over all Resolvers and streamlines them. Created IBootManager, CoreBootManager and WebBootManager
to handle the application initialization including the creation of Resolvers. This means that if people are using the dlls outside
of the web app, they can run the boot strappers to initialize everything.

src/Umbraco.Tests/MacroEngineFactoryTests.cs

@@ -18,10 +18,10 @@ namespace Umbraco.Tests
 			TestHelper.SetupLog4NetForTests();
 
 			//this ensures its reset
-			PluginTypeResolver.Current = new PluginTypeResolver();
+			PluginManager.Current = new PluginManager();
 
 			//for testing, we'll specify which assemblies are scanned for the PluginTypeResolver
-			PluginTypeResolver.Current.AssembliesToScan = new[]
+			PluginManager.Current.AssembliesToScan = new[]
 				{
 					this.GetType().Assembly
 				};