Provide support and compatibility for virtualised environments

The Confluence install guide at http://confluence.atlassian.com/display/DOC/Confluence+Installation+Guide currently says "Virtual Environments such as VMware are not recommended and thus not supported for clustered Confluence."

This should be clarified, probably on a new page:

• Explain which configurations, if any, are supported under VMWare or similar virtualisation. Are the Standalone and EAR/WAR under supported application servers considered supported if virtualised?
• Make recommendations on which use cases/loads have acceptable performance when using a virtualised application server
• Advise if testing shows that database cannot be virtualised due to performance impact
• Add reasons why clustering is unsupported/incompatible
• Link to any known bugs