Feature/initial cut

parses disk io events from the stream and emits disk name if operation is slower than a threshold. The tracker consumes output of parser flowlet and performs analysis to detect slow disks. Since the tracker flowlet performs dataset operations it may be slower than the parser flowlet that performs all job in memory. Thus it is a good idea to have multiple of tracker flowlet instances. In the flow specification below with start with single parser and two tracker flowlets.