Initialize dom0 label

It is required property. Additionally, define icon_path to None,
otherwise it tries to access dom0.dir_path, which isn't set.

qubes/app.py

@@ -872,7 +872,8 @@ class Qubes(qubes.PropertyHolder):
             self.pools[name] = self._get_pool(**config)
 
         self.domains.add(
-            qubes.vm.adminvm.AdminVM(self, None, qid=0, name='dom0'))
+            qubes.vm.adminvm.AdminVM(self, None, qid=0, name='dom0',
+                label='black'))
 
     @classmethod
     def create_empty_store(cls, *args, **kwargs):

qubes/vm/adminvm.py

@@ -143,6 +143,9 @@ class AdminVM(qubes.vm.qubesvm.QubesVM):
         '''
         raise qubes.exc.QubesVMError(self, 'Cannot suspend Dom0 fake domain!')
 
+    @property
+    def icon_path(self):
+        return None
 
 #   def __init__(self, **kwargs):
 #       super(QubesAdminVm, self).__init__(qid=0, name="dom0", netid=0,