Fix for U4-5564

If umbracoUseSSL is set to true, change makes GetCurrentServerUmbracoBaseUrl() return HTTPS URL.  Also overrides ApplicationContext.Current.OriginalRequestUrl to use Port 443 instead of originally loaded port.
Happy for you to review, but I've reverted the code in the umbraco module here: f60884e79690386f942f7cb1b9b8bf0a19972cec 

There shouldn't be any need to alter the OriginalRequestUrl.