downgrade 'No network configured!' to debug log level

Based on the details in bug 1191044, a user can cause the warning
'No network configured!' if they boot an instance in a tenant that
has no neutron networks set up.

Tempest doesn't create a network for every test that creates a nova
instance. The lack of a network is not a sign of something wrong with
nova so a warning log is too much. Move to debug instead.

This should help reduce the amount of warnings that occur on every
tempest run.

Also drop the exclamation mark.

Change-Id: I6bc4e46aa5a72645c72f7232627c7aa9efd2591d
Related-Bug: #1191044
libvirt: Convert more tests to use instance objects

Convert a bunch more test cases over to use objects.Instance
instead of a dict()

Blueprint: libvirt-driver-class-refactor
Change-Id: I4f34c9c795f99e56dd6ca27be237e8c2252f782e
Only check db/api.py for session in arguments

We were checking both db/api.py and db/sqlalchemy/api.py for session
in db apis, but db apis are only defined externall in db/api.py. This
rule will falsely match on non-api methods in db/sqlalchemy/api.py
which take a session argument. Passing the session around within this
module is considered a good thing.

Change-Id: Ibf5d1284b44013c736b6b70ca4fa5d706c365c7d
fix import of oslo.concurrency

It's now oslo_concurrency, and importing the old symbol triggers a
deprecation warning. There were 2 instances of this unfixed.

Change-Id: Ib63da2d845843410634a1df0261af33b973daf32
Merge "fix import of oslo.concurrency"
Merge "libvirt: Convert more tests to use instance objects"
Merge "Only check db/api.py for session in arguments"
Merge "downgrade 'No network configured!' to debug log level"