Merge pull request #232 from cdunn2001/fix-snprintf

Fix snprintf

Well, it passes Travis. But when we have time, we should clean up how snprintf is used in both reader and writer.

Author: cdunn2001

Diff for: src/lib_json/json_writer.cpp

@@ -29,7 +29,7 @@
 
 #if defined(_MSC_VER) && _MSC_VER < 1500 // VC++ 8.0 and below
 #define snprintf _snprintf
-#else
+#elif __cplusplus >= 201103L
 #define snprintf std::snprintf
 #endif