Added optional scope to log4j InstrumentedAppender

Hi,

we have two different log4j appenders in our project and wanted to meter them individually. To achieve this, we revised the existing InstrumentedAppender and made the scope configurable through a new parameter "Scope". If no explicit scope is configured, the default behavior is to use no scope as the current InstrumentedAppender does.

Kind regards,
Janko Heilgeist, QAware GmbH