Code Review & Apache Pig Load/Store

Code Review:
* ArrayList to List
* better exception handling

Apache Pig Store/Load
* introduction of [nullabletuple,nullabletuple] writer (NullableTupleSequenceFileStoreFunc.java)
* extended loader for [nullabletuple,nullabletuple] reading (RichSequenceFileLoader.java)

SequenceFileDemo
* ____SequenceFileWriteDemo.java
* ____SequenceFileReadDemo.java