Display date and time based on phone's preferences.

In StringsUtils, add formatDateTime, formatTime, formatElapsedTime.

Note that verified when sending to Google Docs, no longer need
to always show the hours when displaying total time and moving time.

MyTracks/src/com/google/android/apps/mytracks/StatsUtilities.java

@@ -153,7 +153,7 @@ public class StatsUtilities {
   }
 
   public void setTime(int id, long l) {
-    setText(id, StringUtils.formatTime(l));
+    setText(id, StringUtils.formatElapsedTime(l));
   }
 
   public void setGrade(int id, double d) {