Update CaConfig and ClientCaItem. Add INFO packet encoding and decoding.

Change-Id: I2118bfee05640ddbf20643fa07bf4c91eb7ebd06
diff --git a/tests/unit-tests/ca.conf.test3 b/tests/unit-tests/ca.conf.test3
index f12eabb..b330134 100644
--- a/tests/unit-tests/ca.conf.test3
+++ b/tests/unit-tests/ca.conf.test3
@@ -1,10 +1,9 @@
 {
   "ca-prefix": "/ndn",
-  "issuing-freshness": "720",
-  "validity-period": "360",
   "ca-info": "ndn testbed ca",
+  "max-validity-period": "86400",
   "supported-challenges":
   [
-      { "type": "PINN" }
+      { "challenge": "ABC" }
   ]
 }
\ No newline at end of file