ForwardingStrategy removes PIT if interest wasn't propagated.  Updated
Limits interface (adding config options). Small randomization for decay
frequency in PerFibLimits strategy.
diff --git a/model/ndn-face.h b/model/ndn-face.h
index d22e073..7741c1e 100644
--- a/model/ndn-face.h
+++ b/model/ndn-face.h
@@ -92,7 +92,7 @@
   /**
    * @brief Get reference to Limits object
    */
-  inline Ptr<Limits>
+  inline Limits&
   GetLimits ();    
   
   /**
@@ -255,10 +255,10 @@
   return !(*this == face);
 }
 
-inline Ptr<Limits>
+inline Limits&
 Face::GetLimits ()
 {
-  return m_limits;
+  return *m_limits;
 }