Remove nova v2 client in ListSnapshotImagesTest

ListSnapshotImagesTest should only use nova v3 client for creating
snapshot as the similar test which uses nova v2 client already exist
in nova v2 images api tests(compute/images/test_list_image_filters.py).
This patch removes nova v2 client from ListSnapshotImagesTest.

Change-Id: I04e34f7cd34f760d7bc1361a3037c1f1fe1341d8
Closes-Bug: #1311712
Test script for CRUD operations on regions

Adds test_regions.py test script to identity v3.
Also adds related XML and JSON supporting methos in client file
region_client.py. Modified the identity base.py and common file
clients.py with details about region_client.
The test cases in the test script are
test_create_update_get_delete_region,
test_create_region_with_specific_id and
test_list_regions.

Change-Id: Ib0f07d04f6c31729bacdcfde065777e64fb76333
Verify 'update-server-metadata' APIs attributes

This patch verifies the response attributes of 'update-server-metadata'.

The response attributes of v2 and v3 are the same:
{
    "metadata": {
        "foo": "Foo Value"
    }
}

Response code for V3 API is 201.

Partially implements blueprint nova-api-attribute-test

Change-Id: If70c4cd31ed513276d0a714edc06d4878913ec48
Consolidate _check_public_network_connectivity into NetworkScenarioTest

test_network_advanced_server_ops.py and test_network_basic_ops.py both
have similar _check_public_network_connectivity methods that do the same
thing but handle errors slightly different.

This change consolidates the common code in the parent class and uses
the more robust error handling / diagnostic debug logging of the two.

A follow-on change will do the same for
_check_tenant_network_connectivity.

Partial-Bug: #1323674

Change-Id: I412c9949fb99df950fdde4daab4b1b4f34396d56
Consolidate _check_tenant_network_connectivity in NetworkScenarioTest

Moves _check_tenant_network_connectivity into the parent class for the
basic/advanced network scenario tests and keeps the better diagnostic
debug logging of the two in the common version.

Closes-Bug: #1323674

Change-Id: I4d3f7368e25405fc8baaf23ed1c95a65aef724b7
Merge "Consolidate _check_public_network_connectivity into NetworkScenarioTest"
Merge "Consolidate _check_tenant_network_connectivity in NetworkScenarioTest"
Use correct base test class for test_stress unit tests

This commit switches the stress test unit tests to use the correct
base test class. It was previously using the tempest test base test
class instead of the unit test one.

Change-Id: I518d5b50abbd8c54335e7d5f1a53e0c1b6e36673
Merge "Test script for CRUD operations on regions"
Merge "Remove nova v2 client in ListSnapshotImagesTest"
Merge "Verify 'update-server-metadata' APIs attributes"