Code Cleanup - removed formatTimeDeltaDays

- Removed util.cpp/formatTimeDeltaDays, as it was a replica of
  util.cpp/formatSeconds with a different signature.  Worthless.

src/util.h

@@ -52,7 +52,6 @@ for (typeof (c) *foreach_p = & (c);                                \
 // util.cpp
 bool confirm (const std::string&);
 void delay (float);
-void formatTimeDeltaDays (std::string&, time_t);
 std::string formatSeconds (time_t);
 int autoComplete (const std::string&, const std::vector<std::string>&, std::vector<std::string>&);
 const std::string uuid ();