security: Fixing compilation errors and providing backward compatible interface for Signature*

This commit includes missed includes and "re-introduction" of
setKeyLocator method into Signature interface.  This method was used in
dependent applications as part of SignatureSha256With(Rsa|Ecdsa) data
structures.

Change-Id: I788f687600bb2729ea8265e23d4a31b990b8ed96
Refs: #1750, #1755
diff --git a/tests/unit-tests/security/test-signature-sha256-rsa.cpp b/tests/unit-tests/security/test-signature-sha256-rsa.cpp
index cd717d7..2fd0c3a 100644
--- a/tests/unit-tests/security/test-signature-sha256-rsa.cpp
+++ b/tests/unit-tests/security/test-signature-sha256-rsa.cpp
@@ -83,6 +83,11 @@
                                 sigInfoBlock.wire() + sigInfoBlock.size(),
                                 encodeSigInfoBlock.wire(),
                                 encodeSigInfoBlock.wire() + encodeSigInfoBlock.size());
+
+  sig.setKeyLocator(Name("/test/another/key/locator"));
+
+  const Block& encodeSigInfoBlock2 = sig.getInfo();
+  BOOST_CHECK(sigInfoBlock != encodeSigInfoBlock2);
 }
 
 BOOST_AUTO_TEST_SUITE_END()