adding Function support
adding support for aggregated attributes
Merge pull request #19 from tishan89/Siddhi-3.0.0

adding disruptor performance testcase
improved selector and selector parser to support groupy
adding clone method to Executors
adding attributeAggregators
adding AttributeProcessor and AttributeExecutors
support parsing of groupby aggregated attributes
modified PartitionStreamreceiver
adding comments
merge remote tracking branch sacjaya/Siddhi-3.0.0
merge remote tracking branch sacjaya/Siddhi-3.0.0