DB drivers and NbApi does not match db_api

[Lihi Wishnitzer]

The described API in db_api in not implemented as-is in our drivers.
Also, The usage of NbApi in the drivers, is not as db_api scribes it (but how the drivers are implemented).
For example:
NbApi.get_all uses get_all_entries.
In db_api, get_all_entries throws an exception, but NbApi.get_all does not handle with it.
If our Cassandra or Zookeeper deployments will throw that exception, our controller will crash (Redis and etcd does not throw this exception).

[Omer Anson (omer-anson)]

Adding requirement to this bug: A fullstack test that verifies the DB API of the chosen implementation.

[OpenStack Infra (hudson-openstack)]

Related fix proposed to branch: master
Review: https://review.openstack.org/494247

[OpenStack Infra (hudson-openstack)]

Reviewed: https://review.openstack.org/494247
Committed: https://git.openstack.org/cgit/openstack/dragonflow/commit/?id=eea8229c9c3bb567201a81230af569b7f5ac8838
Submitter: Jenkins
Branch: master

commit eea8229c9c3bb567201a81230af569b7f5ac8838
Author: Omer Anson <email address hidden>
Date: Wed Aug 16 18:43:40 2017 +0300

    Add fullstack tests for DB API

    Change-Id: I70b6e6c52da6a9d4751b43dddf6d9336dcb3f00e
    Related-Bug: #1709040

[OpenStack Infra (hudson-openstack)]

Related fix proposed to branch: master
Review: https://review.openstack.org/507064

[OpenStack Infra (hudson-openstack)]

Reviewed: https://review.openstack.org/507064
Committed: https://git.openstack.org/cgit/openstack/dragonflow/commit/?id=596f73814a0ac174f81292625f96e1b200df3294
Submitter: Jenkins
Branch: master

commit 596f73814a0ac174f81292625f96e1b200df3294
Author: Omer Anson <email address hidden>
Date: Mon Sep 25 14:28:20 2017 +0300

    verify db_driver.get_all_* returns empty list

    Add a test that verifies that db_driver.get_all_entries and get_all_keys
    return an empty list even for non-existent tables.

    Related-Bug: #1709040
    Change-Id: Idb29e8920af2bcdede9e83fe4431c3270da7a0bf