title: Why does "pip install" not include my package_data files?
body: <p>I can't figure out why when I run pip install ../path_to_my_proj/ (from a virtualenv) none of the data files are copied across to the sitepackage/myproj/ folder. The python packages are copied across correctly.</p>
  
  <p>python version 3.4.4</p>
  
  <p>My project directory is like this: </p>
  
  <pre><code>├── myproj
  │   ├── __init__.py
  │   ├── module1.py
  │   └── module2.py
  ├── data_files
  |    ├── subfolder1
  │    |   ├── datafile.dll
  │    |   └── datafile2.dll
  |    └── subfolder2
  │        ├── datafile3.dll
  │        └── datafile4.dll
  |
  ├── MANIFEST.in
  └── setup.py
  </code></pre>
  
  <p>And my MANIFEST.in looks like</p>
  
  <pre><code>recursive-include data_files *
  include README.md
  </code></pre>
  
  <p>my setup looks like:</p>
  
  <pre><code>setup(
      name='myproj',
      version='0.1.1',
      install_requires=['requirement'],
      packages=['myproj'],
      include_package_data=True,
  )  
  </code></pre>