fixed bug: crete_folder was not creating experiments dir

solver.py

@@ -94,12 +94,13 @@ class Solver():
 
         self.use_last_checkpoint = use_last_checkpoint
 
-        experiment_directory_path = os.join.path(
+        experiment_directory_path = os.path.join(
             experiment_directory, experiment_name)
         self.experiment_directory_path = experiment_directory_path
 
+        create_folder(experiment_directory)
         create_folder(experiment_directory_path)
-        create_folder(os.join.path(
+        create_folder(os.path.join(
             experiment_directory_path, checkpoint_directory))
 
         self.start_epoch = 1