Fixed compile error in FlumeAppender.createAppender(): the Rfc5424Layout.createLayout() method was refactored to use strongly typed parameters but FlumeAppender was not updated. Also fixed FlumeAppender.createAppender to pass non-null MDCID to Rfc5424Layout.createLayout(): when called from JUnit tests, the @Default annotation does not replace nulls with default values and the null values cause errors downstream. This solved one problem in FlumeAppender JUnit tests but they are still failing... Matt, can you take a look?

git-svn-id: https://svn.apache.org/repos/asf/logging/log4j/log4j2/trunk@1597421 13f79535-47bb-0310-9956-ffa450edef68