changeTitle (locale) {
    this.options.columns.forEach(columnList => {
      columnList.forEach(column => {
        if (column.field) {
          column.title = locale[column.field]
        }
      })
    })
    this.initHeader()
    this.initBody()
    this.initToolbar()
  }
@author: Jewway
@update zhixin wen <wenzhixin2010@gmail.com>