Fix 2 bug in train_and_evaluate.py

fluid/text_matching_on_quora/train_and_evaluate.py

@@ -87,8 +87,8 @@ def evaluate(epoch_id, exe, inference_program, dev_reader, test_reader, fetch_li
 
 
 def train_and_evaluate(train_reader,
-          test_reader, 
           dev_reader,
+          test_reader, 
           network,
           optimizer,
           global_config,
@@ -246,7 +246,10 @@ def main():
    
     # use cuda or not
     if not global_config.has_member('use_cuda'):
-        global_config.use_cuda = 'CUDA_VISIBLE_DEVICES' in os.environ
+        if 'CUDA_VISIBLE_DEVICES' in os.environ and os.environ['CUDA_VISIBLE_DEVICES'] != '':
+            global_config.use_cuda = True
+        else:
+            global_config.use_cuda = False
 
     global_config.list_config()