title: Installing scrapy on ubuntu 14.04 fails with error in cryptography setup command Invalid environment marker
body: <p>I tried installing scrapy on another server. 
  When I run <code>pip install scrapy</code>:</p>
  
  <pre><code>error in cryptography setup command: Invalid environment marker: python_version &lt; '3'
  Complete output from command python setup.py egg_info:
  error in cryptography setup command: Invalid environment marker: python_version &lt; '3'
  
  ----------------------------------------
  Cleaning up...
  Command python setup.py egg_info failed with error code 1 in /tmp/pip_build_root/cryptography
  Storing debug log for failure in /root/.pip/pip.log
  </code></pre>
  
  <p>any ideas please help</p>
  
  <p>Python 2.7.6</p>
  
  <p>I did</p>
  
  <p><code>sudo apt-get install python-dev python-pip libxml2-dev libxslt1-dev zlib1g-dev libffi-dev libssl-dev</code></p>
  
  <p>and</p>
  
  <p><code>sudo apt-get install python-dev python-pip libxml2-dev libxslt1-dev zlib1g-dev libffi-dev libssl-dev</code></p>
  
  <p>I did an <code>sudo apt-get update</code> before that too</p>