title: Proxy setting in gsutil tool
body: <p>I use gsutil tool for download archives from Google Storage.
  I use next CMD command:</p>
  
  <pre><code>python c:\gsutil\gsutil cp gs://pubsite_prod_rev_XXXXXXXXXXXXX/YYYYY/*.zip C:\Tmp\gs
  </code></pre>
  
  <p>Everything works fine, but if I try to run that command from corporate proxy, I receive error:</p>
  
  <pre><code>Caught socket error, retrying: [Errno 10051] A socket operation was attempted to an unreachable network
  </code></pre>
  
  <p>I tried several times to set the proxy settings in .boto file, but all to no avail. 
  Someone faced with such a problem?
  Thanks!</p>