Log the cause of the Exception as well as the Exception itself

[stuart-warren]

Recursively call the relevant getCause() method on the Throwable.

http://logback.qos.ch/apidocs/ch/qos/logback/classic/spi/LoggingEvent.html#getThrowableProxy()
https://logging.apache.org/log4j/1.2/apidocs/org/apache/log4j/spi/LoggingEvent.html#getThrowableInformation()
http://docs.oracle.com/javase/6/docs/api/java/lang/Throwable.html - good multi exception example too for tests