security: Rename security/v2/* to security/*

Security v1-v2 transition has been completed for a while and path
separation is no longer needed. However, this commit preserves
`ndn::security::v2` namespace, but makes it inline.

Some commonly used v2 headers are preserved, but are deprecated and
should be avoided in the dependent software.

Change-Id: I26056cb3d34bcdc0a16e06dea8c1a78c03da2d40
diff --git a/tests/test-home-fixture.hpp b/tests/test-home-fixture.hpp
index 63d5d88..68ffd50 100644
--- a/tests/test-home-fixture.hpp
+++ b/tests/test-home-fixture.hpp
@@ -22,7 +22,7 @@
 #ifndef NDN_TESTS_TEST_HOME_FIXTURE_HPP
 #define NDN_TESTS_TEST_HOME_FIXTURE_HPP
 
-#include "ndn-cxx/security/v2/key-chain.hpp"
+#include "ndn-cxx/security/key-chain.hpp"
 
 #include <cstdlib>
 #include <fstream>
@@ -76,8 +76,8 @@
     }
 
     boost::filesystem::remove_all(m_pibDir);
-    const_cast<std::string&>(security::v2::KeyChain::getDefaultPibLocator()).clear();
-    const_cast<std::string&>(security::v2::KeyChain::getDefaultTpmLocator()).clear();
+    const_cast<std::string&>(KeyChain::getDefaultPibLocator()).clear();
+    const_cast<std::string&>(KeyChain::getDefaultTpmLocator()).clear();
   }
 
 protected: