Added a check to make sure that hte first boot file exists. Put a warning in the logs if it doesn't.
Generate metadata items only once
Merge pull request #481 from axsh/bugfix-crash-when-missing-first-boot-file

Check if first-boot file exists for windows instances.
Merge pull request #482 from axsh/optimization-metadatadrive-generation

Generate metadata items only once
Merge branch 'master' into bugfix-windows-first-boot-file