title: Pip install in windows does not work due to ssl issue
body: <p>I am trying to do <code>pip install</code> to install tensorflow in my computer. I am behind company proxy and I am bypassing SSL cert so normally I would use this command</p>
  
  <p><code>pip --proxy 0.0.0.0:80 --trusted-host pypi.python.org install tensorflow</code></p>
  
  <p>It normally works well but just today <code>pip install</code> keeps throwing SSL certificate error to me:</p>
  
  <pre><code>Collecting tensorflow
    Retrying (Retry(total=4, connect=None, read=None, redirect=None, status=None)) after connection broken by 'SSLError(SSLError(1, '[SSL: CERTIFICATE_VERIFY_FAILED] certificate verify failed (_ssl.c:749)'),)': /simple/tensorflow/
    Retrying (Retry(total=3, connect=None, read=None, redirect=None, status=None)) after connection broken by 'SSLError(SSLError(1, '[SSL: CERTIFICATE_VERIFY_FAILED] certificate verify failed (_ssl.c:749)'),)': /simple/tensorflow/
    Retrying (Retry(total=2, connect=None, read=None, redirect=None, status=None)) after connection broken by 'SSLError(SSLError(1, '[SSL: CERTIFICATE_VERIFY_FAILED] certificate verify failed (_ssl.c:749)'),)': /simple/tensorflow/
    Retrying (Retry(total=1, connect=None, read=None, redirect=None, status=None)) after connection broken by 'SSLError(SSLError(1, '[SSL: CERTIFICATE_VERIFY_FAILED] certificate verify failed (_ssl.c:749)'),)': /simple/tensorflow/
    Retrying (Retry(total=0, connect=None, read=None, redirect=None, status=None)) after connection broken by 'SSLError(SSLError(1, '[SSL: CERTIFICATE_VERIFY_FAILED] certificate verify failed (_ssl.c:749)'),)': /simple/tensorflow/
    Could not fetch URL https://pypi.python.org/simple/tensorflow/: There was a problem confirming the ssl certificate: HTTPSConnectionPool(host='pypi.python.org', port=443): Max retries exceeded with url: /simple/tensorflow/ (Caused by SSLError(SSLError(1, '[SSL: CERTIFICATE_VERIFY_FAILED] certificate verify failed (_ssl.c:749)'),)) - skipping
    Could not find a version that satisfies the requirement tensorflow (from versions: )
  No matching distribution found for tensorflow
  </code></pre>
  
  <p>I tried to use curl and it works:</p>
  
  <p><code>curl -x 0.0.0.0:80 -k -L https://pypi.python.org</code></p>
  
  <p>How is it that curl works but pip does not? And how to make it work using pip?</p>
  
  <p>My environment:</p>
  
  <pre><code>Windows 10
  pip 9.0.3
  curl 7.54.1
  </code></pre>