Remove document model cache invalidation

The cache invalidation is now handled by the file caching app.

Signed-off-by: Roberto Rosario <roberto.rosario@mayan-edms.com>

mayan/apps/documents/models/document_page_models.py

@@ -64,7 +64,7 @@ class DocumentPage(models.Model):
         return partition
 
     def delete(self, *args, **kwargs):
-        self.invalidate_cache()
+        self.cache_partition.delete()
         super(DocumentPage, self).delete(*args, **kwargs)
 
     def detect_orientation(self):
@@ -234,9 +234,6 @@ class DocumentPage(models.Model):
                 )
                 raise
 
-    def invalidate_cache(self):
-        self.cache_partition.purge()
-
     @property
     def is_in_trash(self):
         return self.document.is_in_trash