Support Expressions for logging-levels in the logging subsystem

In former version the logging configuration supports expressions.
The logger-level and handler-thresholds should be support this in AS7.

<console-handler name="CONSOLE">
<level name="${logging.console.threshold:INFO}"/>
...
<logger category="com.arjuna">
<level name="${logging.tx.level}"/>
</logger>
<root-logger>
<level name="${logging.root.level}"/>
...