* Target Ubuntu in Appveyor CI build
AppVeyor has released support for targetting Ubuntu 18.04 environments.
This adds Ubuntu to the list of build images for Appveyor to use.
* Set clone folder to use appveyor defaults
* Check if appveyor provides appveyor-retry by trying to run it
* Minor syntax change
* Minor syntax change
* Skip using appveyor-retry (for now)
* Use forward slash for paths so that it works on both windows and linux
* Implement replacement for appveyor-retry
* Script cleanup
* Remove commented out line
* Only package releases on Windows
* Add the isWindows condition to the deploy stage
