Updated the build manager to find instances based on persisted cache of previous lookups but uses BuildManager to do so, after

some benchmark unit tests against loading a type from an assembly this is about 100% faster. Updated the UmbracoModule to write more diagnostics
for benchmark debugging. Have basically reduced the startup time to approx 50% of what it used to be based on the current
benchmarks run. Previously app startup on my machine was about 5 seconds, now after the first startup it is about 2.5 seconds.

src/Umbraco.Tests/CacheRefresherFactoryTests.cs

@@ -17,7 +17,7 @@ namespace Umbraco.Tests
 			TestHelper.SetupLog4NetForTests();
 
 			//this ensures its reset
-			PluginManager.Current = new PluginManager();
+			PluginManager.Current = new PluginManager(false);
 
 			//for testing, we'll specify which assemblies are scanned for the PluginTypeResolver
 			PluginManager.Current.AssembliesToScan = new[]