[UPDATE] Changed the Node model to fit the new JSON field in node.metadata

https://forge.iscpif.fr/issues/1472

node/models.py

@@ -3,7 +3,7 @@ from django.utils import timezone
 
 from django.contrib.auth.models import User
 
-from django_hstore import hstore
+import jsonfield
 from cte_tree.models import CTENode, CTENodeManager
 # from cte_tree.query import CTEQuerySet
 #from cte_tree.fields import DepthField, PathField, OrderingField
@@ -125,7 +125,7 @@ class Node(CTENode):
     language    = models.ForeignKey(Language, blank=True, null=True, on_delete=models.SET_NULL)
     
     date        = models.DateField(default=timezone.now, blank=True)
-    metadata    = hstore.DictionaryField(blank=True)
+    metadata    = jsonfield.JSONField(blank=True)
 
     ngrams      = models.ManyToManyField(through='Node_Ngram', to='Ngram')