The __future__ module  was used in this context to ensure compatibility
between python 2 and python 3.
We previously dropped the support of python 2.7  and now we only support
python 3 so we don't need to continue to use this module and the imports
Imports commonly used and their related PEPs:
- `division` is related to PEP 238 
- `print_function` is related to PEP 3105 
- `unicode_literals` is related to PEP 3112 
- `with_statement` is related to PEP 343 
- `absolute_import` is related to PEP 328 
The repo is Python 3 now, so update hacking to version 2.0 which
supports Python 3.
fix issues found by flake8.
Checking the unexpected records.
This commit adds unit tests and removes oslo_db dependency.