JSONCPP_USING_SECURE_MEMORY default is 0

Re: #410
diff --git a/include/json/version.h b/include/json/version.h
index dc975ff..6317404 100644
--- a/include/json/version.h
+++ b/include/json/version.h
@@ -13,7 +13,7 @@
 #ifdef JSONCPP_USING_SECURE_MEMORY
 #undef JSONCPP_USING_SECURE_MEMORY
 #endif
-#define JSONCPP_USING_SECURE_MEMORY 1
+#define JSONCPP_USING_SECURE_MEMORY 0
 // If non-zero, the library zeroes any memory that it has allocated before
 // it frees its memory.