Add (optional) Google Protocol Buffers support (example in Tutorial 3).

To use protobuf, run cmake as follows:
cmake -DUSE_PROTOBUF=1 ..
For this, protobuf library has to be installed on the system.

Further changes:
Clean up splitter/merger: default are N-to-1-merger and 1-to-N-splitter.
Fix bug in nanomsg message deallocation.
Setup proper buffer sizes for nanomsg/zeromq via cmake/bash script.
chmod +x for start scripts.

fairmq/FairMQBenchmarkSampler.h

@@ -33,6 +33,7 @@ class FairMQBenchmarkSampler: public FairMQDevice
     virtual string GetProperty(const int key, const string& default_ = "", const int slot = 0);
     virtual void SetProperty(const int key, const int value, const int slot = 0);
     virtual int GetProperty(const int key, const int default_ = 0, const int slot = 0);
+
   protected:
     int fEventSize;
     int fEventRate;