*  Added support for a GpioController.shutdown() method to cleanup
terminate all Pi4J threads and executors.
     https://github.com/Pi4J/pi4j/issues/9
  *  Added support for a user-definable ExecutorServiceFactory to allow
user program to provide the implementation
     for executor service instances and managed thread pools.  
     https://github.com/Pi4J/pi4j/issues/10
  *  Fixed 'java.util.concurrent.RejectedExecutionException' issue where
there were not 
     enough default thread in the pool for concurrent tasks.
     https://github.com/Pi4J/pi4j/issues/31
  *  Fixed issue where SerialDataMonitorThread was not shutting down on
program exit.
     https://github.com/Pi4J/pi4j/issues/33
  *  Fixed issue where hard-float ABI was not detected properly when
using Oracle JDK 8 early access edition.
     https://github.com/Pi4J/pi4j/issues/26