#31 API POST/PUT Intervention

* splits code in smaller, reusable methods
* adds put method to view
* adds update_model_from_json() method

api/utils/serializer/serializer.py

@@ -78,6 +78,20 @@ class AbstractModelAPISerializer:
         serialized_data = self.model_to_geo_json(entry)
         return serialized_data
 
+    @abstractmethod
+    def update_model_from_json(self, id, json_model, user):
+        """ Updates an instance from given json data
+
+        Args:
+            id (str): The instance's to be updated
+            json_model (dict): JSON data
+            user (User): The performing user
+
+        Returns:
+
+        """
+        raise NotImplementedError("Must be implemented in subclasses")
+
     @abstractmethod
     def create_model_from_json(self, json_model, user):
         """ Creates a new instance from given json data