TODO: check if instance already exists and this is not meant to create it but modify it, not supported by current code which always tries to create when 'present'.
Several azure fixes/improvements, including:
* Improve failure message when python-azure is not installed
* Improve required argument handling
* Fixes a traceback on instance termination when the variable
'deployment' was not set.
* Fixes a traceback (#8298) when creating instances using the newer SDK
* Fixed error messages to be more descriptive
* Removed direct use of subprocess module and replaced it with calls
to module.run_command
* Changed AZURE_MANAGEMENT_CERT_PATH to be just AZURE_CERT_PATH, which
matches what is expected by the inventory script
