Configure a web site - logging clarifications

1) Guidance added on when to use Windows Azure Storage vs. File System storage for web server logging
2) Note added on how to create a storage account and blob container via the Azure portal, which needs to be done before the Windows Azure Storage option can be selected.
3) Clarification that logs roll over when using File System and quota is reached
4) Clarification that Storage Account logs do not roll over but that retention period can be set (as it can for File System).