limits: Introducing modularity for Interest limits

Now ndn::Limits object can be aggregated on a face/FIB entry. A
forwarding strategy module is responsible in creating an appropriate
implementation of the Interest limits module.
diff --git a/wscript b/wscript
index 9b7b52d..8712817 100644
--- a/wscript
+++ b/wscript
@@ -94,7 +94,7 @@
         "model/fw/ndn-forwarding-strategy.h",
         "model/fw/ndn-fw-tag.h",
 
-        "utils/batches.h",
+        # "utils/batches.h",
         "utils/ndn-limits.h",
         # "utils/weights-path-stretch-tag.h",