themes.json: add stat of tries count

admin/api_theme.go

@@ -20,6 +20,7 @@ type exportedExercice struct {
 	Title  string `json:"title"`
 	Gain   int64  `json:"gain"`
 	Solved int64  `json:"solved"`
+	Tried  int64  `json:"tried"`
 }
 
 type exportedTheme struct {
@@ -43,6 +44,7 @@ func exportThemes() (interface{}, error) {
 						exercice.Title,
 						exercice.Gain,
 						exercice.SolvedCount(),
+						exercice.TriedTeamCount(),
 					}
 				}
 				ret[fmt.Sprintf("%d", theme.Id)] = exportedTheme{