Fix ICAT datetime in GUI. Refs #8209.

- Sorting should happen only when data is in the table.
- Changed the format of dates to allow them to be sorted easier.

Code/Mantid/Framework/ICat/src/ICat4/ICat4Catalog.cpp

@@ -360,12 +360,12 @@ namespace Mantid
             // Again, we need to check first if start and end date exist prior to insertion.
             if (investigation->startDate)
             {
-              std::string startDate = formatDateTime(*investigation->startDate, "%d-%m-%y");
+              std::string startDate = formatDateTime(*investigation->startDate, "%F");
               savetoTableWorkspace(&startDate, table);
             }
             if (investigation->endDate)
             {
-              std::string endDate = formatDateTime(*investigation->endDate, "%d-%m-%y");
+              std::string endDate = formatDateTime(*investigation->endDate, "%F");
               savetoTableWorkspace(&endDate, table);
             }
           }

Code/Mantid/MantidQt/MantidWidgets/src/ICatSearch2.cpp

@@ -206,10 +206,6 @@ namespace MantidQt
       table->setSortingEnabled(false);
       table->verticalHeader()->setVisible(false);
 
-      // Sort by endDate with the most recent being first.
-      table->sortByColumn(4,Qt::DescendingOrder);
-      table->setSortingEnabled(true);
-
       // Set the height on each row to 20 for UX improvement.
       for (size_t i = 0; i < numOfRows; ++i)
       {
@@ -703,6 +699,10 @@ namespace MantidQt
 
       // Show only a portion of the title as they can be quite long.
       resultsTable->setColumnWidth(headerIndexByName(resultsTable, "Title"), 210);
+
+      // Sort by endDate with the most recent being first.
+      resultsTable->setSortingEnabled(true);
+      resultsTable->sortByColumn(4,Qt::DescendingOrder);
     }
 
     /**