Get rid of sys.executable usage

That makes things worse not better. It causes "python setup.py test" to
fail if pyflakes isn't installed already.

test_autoflake.py

@@ -4,6 +4,7 @@
 """Test suite for autoflake."""
 
 from __future__ import unicode_literals
+from __future__ import print_function
 
 import contextlib
 import io
@@ -778,8 +779,7 @@ def test_end_to_end(self):
 x = os.sep
 print(x)
 """) as filename:
-            process = subprocess.Popen([sys.executable,
-                                        './autoflake',
+            process = subprocess.Popen(['./autoflake',
                                         '--imports=fake_foo,fake_bar',
                                         filename],
                                        stdout=subprocess.PIPE)
@@ -800,8 +800,7 @@ def test_end_to_end_with_remove_all_unused_imports(self):
 x = os.sep
 print(x)
 """) as filename:
-            process = subprocess.Popen([sys.executable,
-                                        './autoflake',
+            process = subprocess.Popen(['./autoflake',
                                         '--remove-all',
                                         filename],
                                        stdout=subprocess.PIPE)
@@ -820,8 +819,7 @@ def test_end_to_end_with_error(self):
 x = os.sep
 print(x)
 """) as filename:
-            process = subprocess.Popen([sys.executable,
-                                        './autoflake',
+            process = subprocess.Popen(['./autoflake',
                                         '--imports=fake_foo,fake_bar',
                                         '--remove-all',
                                         filename],