Fixing flake8 warnings and errors

flake8 . --count --exit-zero --max-complexity=10 --max-line-length=127 --statistics --exclude benchmark

Excluding the benchmark directory (due to protobuf generated files)
Also removing some Python2 specific code

test/test_object.py

@@ -7,7 +7,7 @@ this_dir = os.path.dirname(__file__)
 
 @pytest.fixture
 def addressbook():
-     return capnp.load(os.path.join(this_dir, 'addressbook.capnp'))
+    return capnp.load(os.path.join(this_dir, 'addressbook.capnp'))
 
 
 def test_object_basic(addressbook):