Renamed RunningTask.onNext() to RunningTask.send()
 * Added a method `RunningTask.send(byte[])`
 * Deprecated `RunningTask.onNext(bye[])`
 * Added the implementation in `RunningTaskImpl`
 * Updated all examples to ose `send(bye[]`
This addresses #777:

  * Added `DriverServiceConfiguration` to allow services to bind to the same events an application can, but without overriding the defaults like in `DriverConfiguration`
  * Added named parameters for all the events in `c.m.r.d.parameters`. Their names are the same as for the application handler names, but prefixed with `Service`
  * Updated `EvaluatorMessageDispatcher` with these new events.
  * Added the new named parameter `DriverSingletons` to generalize the approach taken via the class `DriverSingletons`
Merge branch 'master' of github.com:Microsoft-CISL/REEF into weimer_777
Merge branch 'master' into weimer_789
Merge branch 'master' of https://github.com/Microsoft-CISL/REEF into shravan_groupcomm_interfaces