show edited time at the top of the article

[imaegoo]

Task

• 1. Show edited time at the top of the article when edited time is different with created time.
• 2. Full language support.
• 3. Show absolute time when user hover on relative time.
• 4. Show a yellow bar about edited time information. (just like the image in feature of last update notifier #437)

Preview

@ppoffice
I can not finish task 2 without help, and I am not sure whether we need to implement task 4