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

buildutils/__init__.py

@@ -2,6 +2,7 @@
 
 Largely adapted from h5py
 """
+# flake8: noqa F401 F403
 
 from .msg import *
 from .config import *