Allow relative-time to handle future dates

Why are we soooo concerned with the past? The future is where it's at!!! :rocket: :dizzy: 

We are looking at starting to use web components for travel applications and many of the dates and times associated are in the future. (I did find one lone place for future dates on GitHub, the milestone due date...so it at least has _some_ GH application.)

This PR adds relative-time results that are based off of the same time-ago intervals, just oriented towards the future. "3 days from now", "1 year from now", etc. It also adds a "time-until" option to counter "time-ago" in which the browser will ALWAYS give a future date.

There are several structural changes I made in able to do this so please take a look and provide any feedback.  

Open to any feedback, especially on the wordage...I went back and forth between "3 days from now" and "in 3 days"