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
Merge "Configure logging format flexibly"