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-dns.cpp b/tests/unit-tests/util/test-dns.cpp
index 94cf027..6eeb6e0 100644
--- a/tests/unit-tests/util/test-dns.cpp
+++ b/tests/unit-tests/util/test-dns.cpp
@@ -44,7 +44,7 @@
             bool isValid,
             bool shouldCheckAddress = false)
   {
-    std::cout << "Resolved to: " << resolvedAddress << std::endl;
+    BOOST_TEST_MESSAGE("Resolved to: " << resolvedAddress);
 
     ++m_nSuccesses;