include_package_data set to True by default

All the files present in git were include in the package.

To reproduce:

$ git init
$ mkdir foo
$ touch foo/test.txt
$ touch foo/__init__.py

$ cat setup.py
from setuptools import setup
setup(
    setup_requires=['pbr'],
    pbr=True)

$ cat setup.cfg
[metadata]
name = foo

[files]
packages =
    foo

$ python setup.py bdist_wheel # foo/test.txt not include
$ git add foo/test.txt
$ python setup.py bdist_wheel # foo/test.txt include

But, I don't want to include all the files in my wheel.