Fix load balancer scenario if no tenant network

The load balancer scenario is currently dependent on isolated
tenant networking.  This updates it to allow it to pass in environments
where tenant networking is not present (ie, a shared cross-tenant network).
If a network cannot be resolved by tenant, it will be resolved by the
configured private network name as a fallback and its associated subnet
will be used.

Change-Id: Idbac7c10669a0e2db518223cdd762313aa752876
(cherry picked from commit 3e9e99fb7d7c43b5a6340919f4f1f611f387cbbb)
Some scenario tests do not delete network resources

The ScenarioTest class does not destroy isolated creds upon tearDown.
As several scenarios create network resources through the class
tempest.common.IsolatedCreds, a missing cleanup results in network
resources not being removed.

Change-Id: Id0a0c196b5780888cf71e1f0cfae0931f854ef43
Avoid to iterate over empty list in DictMismatch

It is a little optimization of describe function. If there wasn't found any
differences, there is loop iterating over empty list. It isn't necessary,
because condition a few lines above do the same.

Change-Id: I65067801281c8703f7fa4d1430dcc578d28c3542
Only log console log if nova supports consoles

If a scenario test fails during ssh the standard procedure is to log
the console for the server. However, this can only be done if nova
supports consoles. This commit adds a check to see if nova supports
getting the console for a server before it attempts to do it.
Otherwise if nova doesn't support getting the console and an ssh
connection fails the test will fail on getting a console and not the
ssh connection. It looks like this check wasn't added during the
scenario test port to the tempest clients.

Change-Id: I681b3065d86cd31837a9ef5d91d25847fa47a8f4
Check port's status also in show port tests

Check for port's status in test_show_port by comparing complete dict

Change-Id: I95ff3a6d51c539c59bcb9cb02e16d6da7fbadadd
Merge "Check port's status also in show port tests"
Merge "Only log console log if nova supports consoles"
Merge "Fix load balancer scenario if no tenant network"
Merge "Avoid to iterate over empty list in DictMismatch"
Merge "Some scenario tests do not delete network resources"
Merge branch 'master' of https://github.com/openstack/tempest