add debug out for command line args

binder/start

@@ -6,4 +6,7 @@ import os
 argv = sys.argv[1:] + ['--config', 'binder/jupyter_notebook_config.py']
 print(argv)
 
+with open('startup_args.txt', 'w') as fid:
+    fid.write(str(argv))
+
 os.execv(shutil.which(argv[0]), argv)