Added param to configure mdc variables to be extracted before logging. Currently AccessLogValve runs after filterchain and therefore after the MDC has been cleared in most cases. To fix
Added AccessLogFilter. Also supports MDC though now not needed for original usecase.
AccessLogFilter now delegates logging to the underlying log framework. This distances the servlet from the remote connection configuration
Merge pull request #1 from TheHound/AddMDCFilter

Add AccessLogFilter