2.6.2 install error
I just added that, maybe I needed to add it to `MANIFEST.in`... I pushed a new release, 2.6.3. Will you let me know if that fixes it?
 2.6.3 builds fine, thank you.

The build also succeeded when I temporary uninstalled Cython. Since you did not modify the install instructions in the documentation, I assume that Cython did not become a mandatory build dependency for this new peewee version?
 Cython is an optional dependency, but I had forgotten to include the cython module in the package data I believe. I can add info to the docs though, that's a good idea. Thanks for reporitng this!

I do setup.py install because I am packaging the source code tarball into a personal package for the Linux distribution that I'm using (it's Slackware64-14.1 with Python 2.7.5) and I'm getting this traceback for peewee-2.6.2:

```
Traceback (most recent call last):
  File "setup.py", line 14, in <module>
    ext_modules = cythonize('playhouse/speedups.pyx')
  File "/usr/lib64/python2.7/site-packages/Cython/Build/Dependencies.py", line 754, in cythonize
    aliases=aliases)
  File "/usr/lib64/python2.7/site-packages/Cython/Build/Dependencies.py", line 649, in create_extension_list
    for file in nonempty(extended_iglob(filepattern), "'%s' doesn't match any files" % filepattern):
  File "/usr/lib64/python2.7/site-packages/Cython/Build/Dependencies.py", line 103, in nonempty
    raise ValueError(error_msg)
ValueError: 'playhouse/speedups.pyx' doesn't match any files
```

It did not happen before, for 2.6.1 and earlier versions.

I have Cython-0.22 installed, but I'm pretty sure I installed that as dependency for something else, not for peewee.

I have also skimmed through the README and had a look at http://docs.peewee-orm.com/en/latest/peewee/installation.html, but could not find any useful hints.

What additional steps should I take for peewee-2.6.2 so setup.py build/install succeeds?

Thanks.
