Akshay Agarwal 1e4ab34cd7 Implement a formatter for relative dates.
Signed-off-by: Adrien Destugues <pulkomandy@pulkomandy.tk>

It can give results such as "in 2 hours", "2 days ago", etc.
This is different from BDurationFormat which will just say "1 hour, 2
minute and 36 seconds"
2017-08-25 21:14:27 +02:00
..
2015-11-09 18:01:18 +01:00
2015-11-12 22:24:16 +01:00
2017-07-16 11:35:42 +02:00
2017-07-29 12:27:50 +02:00