Import order cleanup

According to
https://github.com/openstack-dev/hacking/blob/master/HACKING.rst#imports
imports must be ordered by the full module path by the below template

{{stdlib imports in human alphabetical order}}
\n
{{third-party lib imports in human alphabetical order}}
\n
{{project imports in human alphabetical order}}
\n
\n
{{begin your code}}

Change-Id: Ia517e629d557133fca1a4927020a93e9e2abf3f9
Merge "Import order cleanup"