Upgrade flake8-import-order version to 0.17.1

Full py3 compatible version.
Add all Python3 modules to stdlib list.
Also includes fix to an enum34 dependency bug.

Change-Id: I5eda08276c267c0866067bad1daa73513019b9b6

test-requirements.txt

@@ -4,7 +4,7 @@
 
 # pep8
 hacking>=3.0,<3.1.0 # Apache-2.0
-flake8-import-order>=0.13 # LGPLv3
+flake8-import-order>=0.17.1 # LGPLv3
 # documentation
 doc8>=0.6.0 # Apache-2.0
 sphinx!=1.6.6,!=1.6.7,!=2.1.0,>=1.6.2 # BSD