feat(users): use displayName alternative first name and last name

modules/core/client/app/trans-string-en.js

@@ -221,8 +221,7 @@
       PASSWORD_REQ: 'Password Requirements',
       P_REQUIRED: 'Password is required.',
       FORGOT_PASSWORD: 'Forgot your password?',
-      FN_REQUIRED: 'First name is required.',
-      LN_REQUIRED: 'Last name is required.',
+      DN_REQUIRED: 'Display name is required.',
 
       NEW_PASSWORD: 'New Password',
       NP_REQUIRED: 'Enter a new password.',
@@ -614,8 +613,6 @@
       RESET_DEFAULT_PICTURE: 'Reset to default picture',
       ADD_VIP_MONTHS: '+ VIP a month',
       USERNAME: 'Username',
-      FIRST_NAME: 'First name',
-      LAST_NAME: 'Last name',
       DISPLAY_NAME: 'Display name',
       INVITED_BY: 'Invited by',
       EMAIL: 'Email',

modules/core/client/app/trans-string-zh.js

@@ -221,8 +221,7 @@
       PASSWORD_REQ: '密码强度检测',
       P_REQUIRED: '密码不能为空.',
       FORGOT_PASSWORD: '忘记了密码?',
-      FN_REQUIRED: '姓氏不能为空.',
-      LN_REQUIRED: '名字不能为空.',
+      DN_REQUIRED: '显示昵称不能为空.',
 
       NEW_PASSWORD: '新密码',
       NP_REQUIRED: '新密码不能为空.',
@@ -614,8 +613,6 @@
       RESET_DEFAULT_PICTURE: '重置为默认图片',
       ADD_VIP_MONTHS: '+ VIP一个月',
       USERNAME: '用户名',
-      FIRST_NAME: '姓',
-      LAST_NAME: '名',
       DISPLAY_NAME: '显示昵称',
       INVITED_BY: '邀请发送人',
       EMAIL: '邮箱',