Enabled H402 flake8 rule

Added support for flake8 H402: one line docstring needs punctuation.

Reasons:
- H402 is disabled in tox.ini, it needs to be enabled to make code
  more flake8 compliant.

Changes:
- Updated tox.ini to enable H402 rule.
- Updated code for H402 violation.
- Updated one word docstrings to be more meaningful.

Change-Id: I5e67b641717c9704ef4b9f6267390561e4840fff
Merge "Enabled H402 flake8 rule"