bitbake: toaster: Toaster GUI Build and Dashboard pages fixes

THis is a large set of fixes for the generic table, Build and
Dashboard pages.

Among the fixes:
* the table remembers which columns to show across refreshes,
based on saving the settings in a cookie
* added column timespent for a build which is  a denormalization
of the completed_on - started_on information due to limits in
computing datetime differences in the SQL engine
* fixed formatting of the time differences
* various sorting header links fixed
* correct error and warning CSS classes applied to the
respective rows
* fixes multiple divide-by-zero error in displaying duration
estimations

(Bitbake rev: 61e3dee55ac577fce1c0ae0fe7e0d3cf644e8ae6)

Signed-off-by: Alexandru DAMIAN <alexandru.damian@intel.com>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>

bitbake/lib/toaster/toastergui/templates/basetable_bottom.html

@@ -38,6 +38,21 @@
 <script>
  $(document).ready(function() {
 
+    // we load cookies for the column display
+    save = $.cookie('_displaycols_{{objectname}}');
+    setting = save.split(';');
+    for ( i = 0; i < setting.length; i++) {
+        if (setting[i].length > 0) {
+            [id, v] = setting[i].split(':');
+            if (v == 'true') {
+                $('.chbxtoggle#'+id).prop('checked', true);
+            }
+            else {
+                $('.chbxtoggle#'+id).prop('checked', false);
+            }
+        }
+    }
+
     $('.chbxtoggle').each(function () {
         showhideTableColumn($(this).attr('id'), $(this).is(':checked'))
     });