Fix Mysql and Postgresql bug

app/Model/CommentHistory.php

@@ -98,7 +98,7 @@ class CommentHistory extends BaseHistory
             LEFT JOIN tasks ON tasks.id=comment_has_events.task_id
             WHERE comment_has_events.project_id = ?
             ORDER BY comment_has_events.id DESC
-            LIMIT 0, '.$limit.'
+            LIMIT '.$limit.' OFFSET 0
         ';
 
         $rq = $this->db->execute($sql, array($project_id));

app/Model/SubtaskHistory.php

@@ -105,7 +105,7 @@ class SubtaskHistory extends BaseHistory
             LEFT JOIN users AS assignees ON assignees.id=task_has_subtasks.user_id
             WHERE subtask_has_events.project_id = ?
             ORDER BY subtask_has_events.id DESC
-            LIMIT 0, '.$limit.'
+            LIMIT '.$limit.' OFFSET 0
         ';
 
         $rq = $this->db->execute($sql, array($project_id));

app/Model/TaskHistory.php

@@ -96,7 +96,7 @@ class TaskHistory extends BaseHistory
             LEFT JOIN columns ON columns.id=tasks.column_id
             WHERE task_has_events.project_id = ?
             ORDER BY task_has_events.id DESC
-            LIMIT 0, '.$limit.'
+            LIMIT '.$limit.' OFFSET 0
         ';
 
         $rq = $this->db->execute($sql, array($project_id));