[FLINK-1070] Change return type of "getBroadcastVariable()" to List.

This closes #105
[FLINK-1075] Removed the AsynchronousPartialSorter.

This closes #104
[FLINK-1079] Fix inconsistent parameter naming
[FLINK-1078] PrintingOutputFormat uses same partition indexing as FileOutputFormat.
[FLINK-1084] Fix broken links in "How to add an operator"
Add Pi approximation Java example

This closes #78
Some simplifications to the PiEstimation example
[streaming] Fixed SlidingWindowStateIterator