mgmt: add certificate generation/export instructions to nfd.conf.sample.in and README.md

rename configuration file's "keyfile" field to "certfile" to reflect usage of
  an NDN certificate
nfd.conf certfile paths are now interpreted as relative to nfd.conf's location

refs: #1332

Change-Id: Ib91cffd3d113ef084bf19e87a85172ddfd16b7eb
diff --git a/daemon/mgmt/config-file.hpp b/daemon/mgmt/config-file.hpp
index 2a94fac..15eca05 100644
--- a/daemon/mgmt/config-file.hpp
+++ b/daemon/mgmt/config-file.hpp
@@ -16,9 +16,9 @@
 typedef boost::property_tree::ptree ConfigSection;
 
 /// \brief callback for config file sections
-typedef function<void(const ConfigSection&, bool)> OnConfig;
+typedef function<void(const ConfigSection&, bool, const std::string&)> ConfigSectionHandler;
 
-class ConfigFile
+class ConfigFile : noncopyable
 {
 public:
 
@@ -37,7 +37,7 @@
   /// \brief setup notification of configuration file sections
   void
   addSectionHandler(const std::string& sectionName,
-                    OnConfig subscriber);
+                    ConfigSectionHandler subscriber);
 
 
   /**
@@ -75,7 +75,7 @@
 
 private:
 
-  typedef std::map<std::string, OnConfig> SubscriptionTable;
+  typedef std::map<std::string, ConfigSectionHandler> SubscriptionTable;
 
   SubscriptionTable m_subscriptions;