Support for Client-Less Drivers

**API-Support for Client-less Drivers**
 * Deprecated REEF.close(), as this won't be supportable without a client
 * Renamed ClientManager to REEFImplementation
 * Added a JobSubmissionHelper to hold Protobuf code of REEFImplementation
 * Moved the launcher parameters into the 1st class space and added a default value to ErrorHandlerRID and ClientRemoteID
 * Added checks for NONE wherever the ClientRemoteID is used.

**Updated the Local Runtime to support Client-less Drivers**
 * Moved ExecutorServiceConstructor to no longer be an inner class.
 * Shutting down the executor in the LocalJobSubmissionHandler.

**Added a demo of how to use the new API**
 * Added a HelloREEFNoClient that contains the version without a client.