title: SpaCy Install (extended) fails with pip install
body: <p>In need of a python module that features a good POS tagger for the German language SpaCy was recommended to me.
  On my Win10 64Bit with Python 3.4 I tried installing SpaCy as stated on its homepage, first preparing the virtualenv (installed partially, windows failed at source .env/bin/activate), then using pip install.
  As this was not quite working, I cloned SpaCy from github via the git cmd and then continued in the windows console using <code>virtualenv .env &amp;&amp; source .env/bin/activate</code> which again failed at "source".
  After that <code>pip install -r requirements.txt</code> fails aswell.</p>
  
  <p>I tried <code>pip install -U spacy</code> then which seemed to work fine (no error messages) but further commands for using SpaCy (installing a model for example), using <code>python -m spacy.en.download --force</code> all fail with <code>Error while finding spec for 'spacy.en.download' (&lt;class 'ImportError'&gt;: No module named 'spacy.attrs')</code>.</p>
  
  <p>What did I do wrong? How can I ensure a smooth install of SpaCy? It's at least in the list when I try <code>pip list</code>.
  Thank you all in advance!</p>