framework: make date/time format locale specific
    
    Hardcoded date/time format may cause confusion in non-english locales since
    both the order of items and delimiters differ between locales.
    
    Before:
      en_US: Wed Mar 25, 2020 07:40 EDT
      ja_JP: 水  3月 25, 2020 07:40 EDT
      cs_CZ: St bře 25, 2020 07:40 EDT
    After:
      en_US: Wed 25 Mar 2020 12:24:22 PM CET
      ja_JP: 2020年03月25日 12時24分22秒
      cs_CZ: St 25. března 2020, 12:24:22