Updating references to the (old) preview portal

This PR contains a number of minor fixes and tweaks where there were references to:
- the Azure Preview Portal, where the preview portal is actually the currently released main portal at `manage.windowsazure.com`
- The 'create a storage account' page had very old instructions for creating an affinity group using the ancient Silverlight portal; updated to target the current main portal at manage.windowsazure.com
- Virtual Machines being a preview feature - this has GA'd a long time ago
- References to AMQP for Service Bus being a preview feature, this shipped in May 2013
- A fix to invalid XML in a UE header

Thanks,
JWilcox