#18 File upload in certain folders

* increases max_size for FileFields --> triggers when the file name will be automatically changed during upload
* adds Http404 Exception in case document file does not exist anymore on the hard drive

ema/models.py

@@ -97,5 +97,6 @@ class EmaDocument(AbstractDocument):
         related_name="documents",
     )
     file = models.FileField(
-        upload_to=generate_document_file_upload_path
+        upload_to=generate_document_file_upload_path,
+        max_length=1000,
     )