Implement the rdci subsystem: group, fieldgroup and dmon

Add the support for rdci subsystem group create, delete and query

Add the support for rdci subsystem fieldgroup create, delete and query

Add the support for rdci dmon system. The dmon system may show the stats every
a few seconds until press Ctrl-C. To cleanup the resources (for example, unwatch),
a signal handler is added.

Change-Id: Ib22a8a43b7083c7c72819ca21145e22702d9ad6c

rdci/include/RdciSubSystem.h

@@ -24,6 +24,7 @@ THE SOFTWARE.
 
 #include <memory>
 #include <string>
+#include <vector>
 #include "rdc_lib/rdc_common.h"
 #include "rdc/rdc.h"
 
@@ -39,6 +40,8 @@ class RdciSubSystem {
      virtual void process() = 0;
      virtual ~RdciSubSystem();
  protected:
+     std::vector<std::string> split_string(const std::string& s,
+            char delimiter) const;
      void show_common_usage() const;
      rdc_handle_t rdc_handle_;
      std::string ip_port_;