setup.py: stop adding numpy to the include path

The removed code predates "build.conf" and should not be necessary on
most (all?) platforms.  Should numpy be missing in the include path, it
can be added using "build.conf".

If this change turns out to cause problems, we can always revert it.

setup.py

@@ -34,12 +34,6 @@ from distutils.command.build import build
 from setuptools.command.sdist import sdist
 from setuptools.command.build_ext import build_ext
 
-try:
-    import numpy
-except ImportError:
-    include_dirs = []
-else:
-    include_dirs = [numpy.get_include()]
 
 CONFIG_FILE = 'build.conf'
 README_FILE = 'README.rst'
@@ -505,9 +499,8 @@ def main():
                     'build_ext': kwant_build_ext,
                     'build_tut': kwant_build_tut},
           ext_modules=maybe_cythonize(extensions()),
-          include_dirs=include_dirs,
-          setup_requires=['numpy > 1.6.1', 'pytest-runner >= 2.7'],
-          tests_require=['pytest >= 2.6.3'],
+          setup_requires=['pytest-runner >= 2.7'],
+          tests_require=['numpy > 1.6.1', 'pytest >= 2.6.3'],
           install_requires=['numpy > 1.6.1', 'scipy >= 0.9', 'tinyarray'],
           extras_require={'plotting': 'matplotlib >= 1.2'},
           classifiers=[c.strip() for c in CLASSIFIERS.split('\n')])