Configure logging format flexibly

Now we can get tempest log file with options in run_tests.sh.
This adds log.py and enables to configure log format more flexibly
using configuration file.
This adds a LoggerAdaptor and a Formatter to output each test name
to log lines.

Implements: blueprint add-logging-configuration

Change-Id: I88cf18bb8bbc152e62ac83a9c7dc26067b7a11bd
diff --git a/tempest/api/image/base.py b/tempest/api/image/base.py
index f12e957..e62d84b 100644
--- a/tempest/api/image/base.py
+++ b/tempest/api/image/base.py
@@ -14,9 +14,8 @@
 #    License for the specific language governing permissions and limitations
 #    under the License.
 
-import logging
-
 from tempest import clients
+from tempest.common import log as logging
 from tempest.common.utils.data_utils import rand_name
 from tempest import exceptions
 import tempest.test