Add option '--no-cert-checks' for 'upload' sub command.

This option allow to bypass verification ssl certification while
establishing connection with Gerrit to upload review.

Change-Id: If2e15f5a273c18a700eb5093ca8a4d5a4cbf80cd
diff --git a/git_config.py b/git_config.py
index e00f6be..fb4377c 100644
--- a/git_config.py
+++ b/git_config.py
@@ -20,6 +20,7 @@
 import json
 import os
 import re
+import ssl
 import subprocess
 import sys
 try:
@@ -604,7 +605,7 @@
     connectionUrl = self._InsteadOf()
     return _preconnect(connectionUrl)
 
-  def ReviewUrl(self, userEmail):
+  def ReviewUrl(self, userEmail, validate_certs):
     if self._review_url is None:
       if self.review is None:
         return None
@@ -637,7 +638,11 @@
       else:
         try:
           info_url = u + 'ssh_info'
-          info = urllib.request.urlopen(info_url).read()
+          if not validate_certs:
+              context = ssl._create_unverified_context()
+              info = urllib.request.urlopen(info_url, context=context).read()
+          else:
+              info = urllib.request.urlopen(info_url).read()
           if info == 'NOT_AVAILABLE' or '<' in info:
             # If `info` contains '<', we assume the server gave us some sort
             # of HTML response back, like maybe a login page.