Avoid unnecessary explicit str() conversion around exceptions

There are number of places like

except Exception as exc:
            LOG.error("Failed to get network: %s", str(exc))

where str() is not needed since %s substitution already does
the same conversion. Also LOG.error could be replaced with
LOG.exception, so argument exc won't be needed at all.

Closes-bug: #1398839

Change-Id: I73cc6e1ce55ade08e7706b99a5ab075f7059a4ef
Move contrib directory to base test directory

This is needed to have post hook apply to both functional and api jobs.

This is aimed at fixing the output for the dsvm-api job in preparation
of the retargatable testing blueprint.

Change-Id: I39e2a7521a7b545a124b1cd42dc79da8986eff93
Update heal_script for alembic 0.7.1

Alembic 0.7.1 contains checks of foreign keys so
method check_foreign_keys is not needed anymore.
Heal script should be updated to make it possible to use alembic
methods.

Closes-bug: #1398417

Change-Id: I7d0ba7f00567ae5a4dd0669ed86d6e8d554ca4ec
tests: drop unit tests that only check default configuration values

Those tests do not add much value and only introduce burden when a
default value should be changed.

Change-Id: I32049399b16338996d6bef342c004d5de2446cf1
Merge "Avoid unnecessary explicit str() conversion around exceptions"
Merge "Update heal_script for alembic 0.7.1"
Merge "Move contrib directory to base test directory"
Merge "tests: drop unit tests that only check default configuration values"