Define hex helper utils

This commit attempts to optimize some code and reduce our dependence on
boost libraries, as the coding standard recommends.  It does this by
introducing a new method, intToHexString, which is a greatly simplified
"to hex" converter that doesn't require std::locale, or stream buffers,
and is very efficient.  This deletes our need for boost::format, as well
as our need for boost::lexical_cast, both of which are fairly heavy
libraries.

Tested:
Unit tests pass.

Signed-off-by: Ed Tanous <edtanous@google.com>
Change-Id: I3b0f6eeb10256f87320adcc0ae9396f6bcbc8740
diff --git a/redfish-core/lib/memory.hpp b/redfish-core/lib/memory.hpp
index 2d647dc..5d508c4 100644
--- a/redfish-core/lib/memory.hpp
+++ b/redfish-core/lib/memory.hpp
@@ -19,9 +19,9 @@
 
 #include <app.hpp>
 #include <boost/container/flat_map.hpp>
-#include <boost/format.hpp>
 #include <registries/privilege_registry.hpp>
 #include <utils/collection.hpp>
+#include <utils/hex_utils.hpp>
 #include <utils/json_utils.hpp>
 
 namespace redfish
@@ -154,7 +154,7 @@
         return;
     }
 
-    aResp->res.jsonValue[key] = (boost::format("0x%04x") % *value).str();
+    aResp->res.jsonValue[key] = "0x" + intToHexString(*value);
 }
 
 inline void getPersistentMemoryProperties(