Support Logging in windows azure and prevent app_data creation.

Don't initialize the providers till after reading the values from the web configs so that empty directories are not created. Use System.Diagnostics.Tracing instead of a file for Azure as in http://www.windowsazure.com/en-us/develop/net/common-tasks/diagnostics-logging-and-instrumentation/#header-1.

Still needed move cache file to creation to memory/storage/caching service.