set the label of StudentInfoActivity
add "request password for private information" preference setting

新增 “密码保护私密信息”配置项
修改 完善密码验证对话框。设置密码InputType，纠正提示信息中的错别字
show dialog if account id or password incorrect

修正 账号ID或密码错误时，显示提示对话框
修改 把StudentInfoActivity改为FragmentActivity
startRefreshAnimation if isUpdating posts onCreateOptionsMenu