avocado.plugins.vm: Add missing name attribute to the test vm attribute

As it was missing, causing an error with the json output.
Signed-off-by: NLucas Meneghel Rodrigues <lmr@redhat.com>

avocado/plugins/vm.py

@@ -36,6 +36,7 @@ class Test(object):
     """
 
     def __init__(self, name, status, time):
+        self.name = name
         self.tagged_name = name
         self.status = status
         self.time_elapsed = time