added configuration 'http_proxy' to allow the usage of a proxy

Author: mbohlool

configuration.py

@@ -89,6 +89,10 @@ def __init__(self):
         # Set this to True/False to enable/disable SSL hostname verification.
         self.assert_hostname = None
 
+	# http proxy setting
+        self.http_proxy_url = None
+
+
     @property
     def logger_file(self):
         """

rest.py

@@ -107,9 +107,14 @@ def __init__(self, pools_size=4, config=configuration):
             kwargs['assert_hostname'] = config.assert_hostname
 
         # https pool manager
-        self.pool_manager = urllib3.PoolManager(
-            **kwargs
-        )
+        if config.http_proxy_url is not None:
+            self.pool_manager = urllib3.proxy_from_url(
+                config.http_proxy_url, **kwargs
+            )
+        else:
+            self.pool_manager = urllib3.PoolManager(
+	        **kwargs
+            )
 
     def request(self, method, url, query_params=None, headers=None,
                 body=None, post_params=None, _preload_content=True, _request_timeout=None):