tests: Small corrections in cases

Changes include:
- disable use of std::cout in DNS test case (use BOOST_TEST_MESSAGE instead)
- renaming test suites for InMemoryStorage cases.  All InMemoryStorage
  cases are grouped under InMemoryStorage super-suite and specific
  implementations are put in Common, Fifo, Lru, Lfu, Persistent suites.

Change-Id: Id42642304b7a06bbabd980c3cb50ddfa26bd349f
diff --git a/tests/unit-tests/util/test-in-memory-storage-lfu.cpp b/tests/unit-tests/util/test-in-memory-storage-lfu.cpp
index 835b804..428d2e3 100644
--- a/tests/unit-tests/util/test-in-memory-storage-lfu.cpp
+++ b/tests/unit-tests/util/test-in-memory-storage-lfu.cpp
@@ -28,7 +28,8 @@
 namespace ndn {
 namespace util {
 
-BOOST_AUTO_TEST_SUITE(UtilInMemoryStorageLfu)
+BOOST_AUTO_TEST_SUITE(UtilInMemoryStorage)
+BOOST_AUTO_TEST_SUITE(Lfu)
 
 BOOST_AUTO_TEST_CASE(FrequencyQueue)
 {
@@ -126,7 +127,8 @@
   BOOST_CHECK_EQUAL(found3->getName(), name3);
 }
 
-BOOST_AUTO_TEST_SUITE_END()
+BOOST_AUTO_TEST_SUITE_END() // Lfu
+BOOST_AUTO_TEST_SUITE_END() // UtilInMemoryStorage
 
 } // namesapce util
 } // namespace ndn