Joda -> JSR-310

[ligi]

You should convert from joda to JSR-310 ( or a backport of it ):
http://blog.joda.org/2014/11/converting-from-joda-time-to-javatime.html

like:
https://github.com/ThreeTen/threetenbp / https://github.com/JakeWharton/ThreeTenABP

[ledor473]

At first we used JSR-310, but to support Android (and JDK 6-7 users) JodaTime was used instead.

If we switch to a backport of JSR-310, I'd prefer to publish separate artifacts:

1. Android/JDK6-7 with the backport as a dependancy
2. JDK8 without the backport