If 'Description' field is omitted in manifest.yaml file, the following
exception will be raised.
murano package-import ./HelloWorld/hello_world.zip
Failed to create package for './HelloWorld/hello_world.zip',
reason: Invalid Murano package E020 Missing required key
"Description" (HTTP 400)
Change-Id: I9096bf1a3dc56e2d9e5c335f4bfefddf0fd60108