Remove pytest command magic from setup.py

To keep things everyone should just run `py.test` directly instead
of via `setup.py`.

setup.py

@@ -1,5 +1,4 @@
 from setuptools import setup, find_packages
-from setuptools.command.test import test as TestCommand
 import sys
 
 version = '4.14'
@@ -17,19 +16,6 @@
 ]
 
 
-class PyTest(TestCommand):
-    def finalize_options(self):
-        TestCommand.finalize_options(self)
-        self.test_args = ['tests']
-        self.test_suite = True
-
-    def run_tests(self):
-        # import here, cause outside the eggs aren't loaded
-        import pytest
-        errno = pytest.main(self.test_args)
-        sys.exit(errno)
-
-
 setup(name='lingua',
       version=version,
       description='Translation toolset',
@@ -64,7 +50,6 @@ def run_tests(self):
           'tests': tests_require,
           'chameleonextractor': ['Chameleon'],
       },
-      cmdclass={'test': PyTest},
       entry_points='''
       [console_scripts]
       polint = lingua.polint:main