Changelog: update for 1.2.1

CHANGELOG.en-US.md

 ## Changelog
 
+### 1.2.1
+
+*2017-02-23*
+
+- Fixed SSR regression in version 1.2.0, #2982
+- Fixed horizontal scroll buttons not showing in Tabs, #2974
+- Fixed wrong calculation of height after the `height` attribute is updated dynamically in Table, #2979
+- Added `cell-dblclick` and `header-dragend` events for Table, #2983 #2988
+- Fixed form items showing a left padding inside an inline Form with a specified `label-width`, #2990
+- Fixed Cascader's dropdown misplaces in some conditions, #2992
+
 ### 1.2.0 Lithium
 
 *2017-02-22*

CHANGELOG.zh-CN.md

 ## 更新日志
 
+### 1.2.1
+*2017-02-23*
+
+- 修复用于 SSR 时报错的问题，#2982
+- 修复 Tabs 左右滚动按钮无法出现的问题，#2974
+- 修复 Table 在动态改变 `height` 属性后高度计算错误的问题，#2979
+- 新增 Table 的 `cell-dblclick` 和 `header-dragend` 事件，#2983 #2988
+- 修复行内表单在指定 `label-width` 时表单元素出现左边距的问题，#2990
+- 修复 Cascader 在某些情况下弹出框位置不正确的问题，#2992
+
 ### 1.2.0 Lithium
 *2017-02-22*