Fix extension for rdf output

src/app/app.py

@@ -53,7 +53,7 @@ def convertUnl(unl, outputs):
 
     # Handle rdf output if any
     if 'rdf' in outputs:
-        fname = '{}/{}.rdf'.format(out_dir, out_name)
+        fname = '{}/{}.ttl'.format(out_dir, out_name)
         with open(fname, 'r') as f:
             res['rdf'] = f.read()
         try: