Reverted back to Throwable instead of Exception for TaskScheduler except now throwing ThreadDeath per JDK explanation: http://docs.oracle.com/javase/7/docs/api/java/lang/ThreadDeath.html

git-svn-id: https://svn.apache.org/repos/asf/roller/trunk@1512867 13f79535-47bb-0310-9956-ffa450edef68