add trainer.py for examples

examples/train.py

+
+import yaml
+from .. trainer.factory import TrainerFactory
+
+if __name__ == "__main__":
+
+    with open('ctr-dnn_train.yaml', 'r') as rb:
+        global_config = yaml.load(rb.read())
+
+    trainer = TrainerFactory.craete(global_config)
+    trainer.run()