Replace tearDown with addCleanup - Part 5

Replace tearDown with addCleanup in:
- cinder/test.py
- cinder/tests/test_migrations.py

Remove empty tearDown methods from:
- cinder/tests/test_hp3par.py
- cinder/tests/test_hplefthand.py
- cinder/tests/test_ibmnas.py
since it does not add any functionality (and empty setUp methods as well).

Infra team has indicated that tearDown should not be used and should
be replaced with addCleanup in all places.

Implements blueprint replace-teardown-with-addcleanup

Change-Id: Id2fdd3e2e1ab8458083697b6ea6714ca019fd00a
Improve consistency of help strings

Fixes include rework of text, missing or extra spaces, wrong
capitalization and no sentence style capitalization.

Co-Authored-By: Diane Fleming <diane.fleming@rackspace.com>
Change-Id: Iddab947ce9597f4a1de885f1f6c0fb0e5ba9dc46
Merge "Replace tearDown with addCleanup - Part 5"
Merge "Improve consistency of help strings"