* add availability set for vm
* add test
* add import
* fix
* add test assert and output
* fix lint and version added
* add null check
* fix mirror
* fix mirror
* azure_rm_virtualmachine: added support for specifying custom image
* Use separate parameter for custom_image, add very basic test
* missed the version_added tag for doco
* removed whitespace I accidentally left in
* merged custom image into the image dict and added more tests
* added one more test