Added PySocks extra requirement

setup.py

@@ -41,5 +41,9 @@ setup(
 
     classifiers = proj_info['classifiers'],
 
-    entry_points = {'console_scripts': proj_info['console_scripts']}
+    entry_points = {'console_scripts': proj_info['console_scripts']},
+
+    extras_require={
+        'socks': ['PySocks'],
+    }
 )