Enabled F403 flake8 rule

Reasons:
- F403 is disabled.
- code contains "import *" statements.

Changes:
- Updates tox.ini to enable F403 rules.
- Updates code for F403 violation.

Change-Id: If932a910c073ae7bffb74908495f35dbc4f4d1f9
Closes-Bug: #1264724
Merge "Enabled F403 flake8 rule"