security: Update Signature abstraction to match 0.1.1 spec

This commit removes intermediate SignatureWithPublicKey data
structure.  All uses of such data structure should be replaced with just
Signature and check that KeyLocator is present (hasKeyLocator()).

Change-Id: I1157e05c6a717ea28df91c4bfd76c7145b520a15
Refs: #1750
diff --git a/tests/unit-tests/security/test-digest-sha256.cpp b/tests/unit-tests/security/test-digest-sha256.cpp
index 94ded5b..264078c 100644
--- a/tests/unit-tests/security/test-digest-sha256.cpp
+++ b/tests/unit-tests/security/test-digest-sha256.cpp
@@ -26,26 +26,25 @@
 
 #include "boost-test.hpp"
 
-using namespace std;
 namespace ndn {
 
 BOOST_AUTO_TEST_SUITE(SecurityTestDigestSha256)
 
-string SHA256_RESULT("a883dafc480d466ee04e0d6da986bd78eb1fdd2178d04693723da3a8f95d42f4");
+std::string SHA256_RESULT("a883dafc480d466ee04e0d6da986bd78eb1fdd2178d04693723da3a8f95d42f4");
 
-BOOST_AUTO_TEST_CASE (Sha256)
+BOOST_AUTO_TEST_CASE(Sha256)
 {
   using namespace CryptoPP;
 
   char content[6] = "1234\n";
   ConstBufferPtr buf = crypto::sha256(reinterpret_cast<uint8_t*>(content), 5);
-  string result;
+  std::string result;
   StringSource(buf->buf(), buf->size(), true, new HexEncoder(new StringSink(result), false));
 
-  BOOST_REQUIRE_EQUAL(SHA256_RESULT, result);
+  BOOST_CHECK_EQUAL(SHA256_RESULT, result);
 }
 
-BOOST_AUTO_TEST_CASE (Signature)
+BOOST_AUTO_TEST_CASE(Signature)
 {
   using namespace CryptoPP;
 
@@ -63,7 +62,9 @@
 
   DigestSha256 sig(testData.getSignature());
 
-  BOOST_REQUIRE(Validator::verifySignature(testData, sig));
+  BOOST_CHECK(Validator::verifySignature(testData, sig));
+
+  BOOST_CHECK_THROW(sig.getKeyLocator(), ndn::SignatureInfo::Error);
 }
 
 BOOST_AUTO_TEST_SUITE_END()