Add support for milliseconds

[debona]

Hi there!

Java Date are precise to milliseconds so I think it would be a good idea for this library to support milliseconds.

Otherwise, you don't have any way of creating two equal dates:

val date     = Dates.of(year = 2016, month = 2, day = 26, hour = 18, minute = 58, second = 31)
val sameDate = Dates.of(year = 2016, month = 2, day = 26, hour = 18, minute = 58, second = 31)
date.equals(sameDate) // => return false!

This PR allow this library to creates two equal dates:

val date     = Dates.of(year = 2016, month = 2, day = 26, hour = 18, minute = 58, second = 31, millisecond = 777)
val sameDate = Dates.of(year = 2016, month = 2, day = 26, hour = 18, minute = 58, second = 31, millisecond = 777)
date.equals(sameDate) // => return true

I think there is no breaking changes and all unit tests should pass.
Don't hesitate to ask me for changes, I really like this library but I need to compare dates equality so I need this changes :)

[debona]

It seems this changes are awaited for few months: #18 #11

[ashishkrishnan]

@hotchemi My team and I hit a blocker when we tried using khronos with Mockito for tests.
The time in production code and the tests differed by few millis, which in turn caused Mockito to return NPE on unmatched fields.

Interesting to note, adding a millis support fixed it.
I think it is good to go for merging!.

Library is rad!! Kudos!

@debona Thanks, you saved us a day.

[debona]

Hey @ashishkrishnan I'm glad to hear it helps other people 👍
@hotchemi any news? This library took a good start, do you plan to maintain it?

[hotchemi]

Oh sorry let me check!

[ashishkrishnan]

@hotchemi @debona any update on this?

[LeoColman]

I believe this lib is dead. Milliseconds is a very necessary feature!