security: fixing bugs and adding methods

1. changing getCertificate to take only one argument, now validation checking is always enforced.
2. changing KSK-... DSK-... to lower case ksk-..., dsk-...
3. adding a addCertificateAsSystemDefault method to facilitate setting default certificate of the system.
4. using static_cast<int> (rather than floor) to round time.
5. sanity checking for key name in SecPublicInfo and SecPublicInfoSqlite3.

Change-Id: Id67af9873efef3df92458ed7a87623f22167c558
diff --git a/include/ndn-cpp/security/identity/sec-public-info-sqlite3.hpp b/include/ndn-cpp/security/identity/sec-public-info-sqlite3.hpp
index 335b724..99dac54 100644
--- a/include/ndn-cpp/security/identity/sec-public-info-sqlite3.hpp
+++ b/include/ndn-cpp/security/identity/sec-public-info-sqlite3.hpp
@@ -127,7 +127,7 @@
    * @return The requested certificate.  If not found, return a shared_ptr with a null pointer.
    */
   virtual ptr_lib::shared_ptr<IdentityCertificate> 
-  getCertificate(const Name &certificateName, bool allowAny);
+  getCertificate(const Name &certificateName);
 
 
   /*****************************************