Timestamps Age Update

[motackt]

Take 2! (from #1655)

I was surprised to see that work on timestamps went ahead so quick, but I hope these features can be added to make it even better!

New Features:

• Users can display the timestamp next to the header
• Timestamps now display how old they are!

Known bugs:

• Peepr post headers have a maximum width that cuts off long timestamps (ie with both relative and absolute time displayed); can fix by changing CSS for peepr post headers, but seems outside scope of this extension?

(Also, I have no idea why that first commit is there, hopefully that's not a problem?)
(Also also, idk why the last edit in timestamps.js is there either bc i didn't make that edit?)

[motackt]

Considering having timestamps that are beside the header float to the right so it aligns with the reblog timestamps, i think it might look neater. Thoughts :?