Feature/initial cut

"The Parser Flowlet parses disk I/O events from the Stream and emits the disk name if the operation is slower than a threshold. The Tracker consumes the output of the Parser Flowlet and performs an analysis to detect a slow disk. Since a Tracker Flowlet performs dataset operations, it may be slower than a Parser Flowlet that performs all processing in memory. Thus, it's a good idea to have multiple Tracker Flowlet instances. In the Flow specification below, we'll start with a single Parser and two Tracker Flowlets."