Elasticsearch 5: Format transport client logs

This commit adds some basic formatting to the transport client logs for
the transport client used in the Elasticsearch 5 binding.

elasticsearch5/src/main/resources/log4j2.properties

 appender.console.type = Console
 appender.console.name = console
 appender.console.layout.type = PatternLayout
+appender.console.layout.pattern = [%d{ISO8601}][%-5p][%-25c{1.}] %marker%m%n
 
 rootLogger.level = info
-rootLogger.appenderRef.console.ref = console
\ No newline at end of file
+rootLogger.appenderRef.console.ref = console