title: ValidationError while running Google adwords client library examples
body: <p>I get the following error when I try to run sample example of Google adwords</p>
  
  <blockquote>
    <p>[root@some v200909]# python get_related_keywords.py  Traceback (most recent call last):   File "get_related_keywords.py", line 53, in 
        page = targeting_idea_service.Get(selector)[0] File "../../aw_api/TargetingIdeaService.py", line 105, in Get
        'TargetingIdea', self.__loc, request)   File "../../aw_api/WebService.py", line 350, in CallMethod
        raise ValidationError(error['data']) aw_api.Errors.ValidationError: Invalid headers for '<a href="https://adwords-sandbox.google.com" rel="nofollow noreferrer">https://adwords-sandbox.google.com</a>', see <a href="http://code.google.com/apis/adwords/docs/developer/adwords_api_sandbox.html#requestheaders" rel="nofollow noreferrer">http://code.google.com/apis/adwords/docs/developer/adwords_api_sandbox.html#requestheaders</a>. [root@some v200909]#</p>
  </blockquote>