imported file must have csv extension

Changed to avoid importing .py file or csv backups

import_csv.py

@@ -191,7 +191,7 @@
         r'(?:[\d\s\w_-]*\s)?'
         r'(?P<model>[\w.]+?)'
         r'(?:@(?P<lang>\w{2,3}(?:@latin|_\w{2})))?'
-        r'(?:.csv)?'
+        r'.csv'
     )
     file_list = list()
     if nmspc.file: