add dependency sock.py (aliyun#184)

fix import socks

Author: wallisyan

aliyun-python-sdk-core/aliyunsdkcore/vendored/requests/packages/urllib3/contrib/socks.py

@@ -24,7 +24,7 @@
 from __future__ import absolute_import
 
 try:
-    import socks
+    from ..packages import socks
 except ImportError:
     import warnings
     from ..exceptions import DependencyWarning