MXS-1810: Add C++ hex conversion functions

Added mxs::to_hex for uint8_t types and uint8_t containers.

server/core/utils.cc

@@ -29,6 +29,7 @@
  */
 
 #include <maxscale/utils.h>
+#include <maxscale/utils.hh>
 
 #include <fcntl.h>
 #include <netdb.h>
@@ -1136,3 +1137,16 @@ long get_processor_count()
 #endif
     return processors;
 }
+
+namespace maxscale
+{
+
+std::string to_hex(uint8_t value)
+{
+    std::string out;
+    out += hex_lower[value >> 4];
+    out += hex_lower[value & 0x0F];
+    return out;
+}
+
+}