Adding an implementation of the SimpleScheduler.

SimpleScheduler takes a single list of tasks, spins up a single resource, executes the tasks in order on the resource, an then shuts the resource down.

Also refactored some subsidiary classes, with the RNG code going to its own file and Parameters into the Simulator file.
Added a test for EventHistory, and fixed the ordering of the recursive methods.
More tests for EventHistory, fixing a few more bugs.
Added PRNG tests.
Adding tests for InitialEvent and TerminalEvent
Added TrackerSuite, fixed another bug in EventHistory.
Added more tests, fixed a bug where Parameters.sampleResourceFailureTime produced negative numbers occasionally.
Added JobSuite, fixed a bug in the Simulator.updateState method.
Adding two more Simulator tests.
More Simulator testing.
Added DirectedGraph implementation.
[SCHED-11] RDDGraph implementation.

Adding an implementation of an RDDGraph.
Partitioning schemes are modeled as Traits (this is so that we can detect when two
subsequent RDDs are co-partitioned, that is, partitioned identically).

Dependencies come in two flavors, "narrow" and "wide," although we _could_ add more
in the future if we wanted.
added RDDTask