Update fromNow plugin

[iamkun]

@aalises

I update the code of fromNow plugin a little bit. Here is the reason:

In previous code, we use resabs !== P[i].v to check if it is singular a month or 2 months.

However, there is some disadvantage of this kind of check, it must be exactly the same time in millisecond, otherwise, it will result 1 month instead of a month

So my solution is, still implement it in Moment.js's way.

We set the output to a range of time. Check the table blew:

Range	Key	Sample Output
0 to 44 seconds	s	a few seconds ago
44 to 44 seconds	ss	44 seconds ago
45 to 89 seconds	min	a minute ago
90 seconds to 44 minutes	mins	2 minutes ago ... 44 minutes ago
45 to 89 minutes	h	an hour ago
90 minutes to 21 hours	hh	2 hours ago ... 21 hours ago
22 to 35 hours	d	a day ago
36 hours to 25 days	dd	2 days ago ... 25 days ago
26 to 45 days	M	a month ago
46 days to 10 months	MM	2 months ago ... 10 months ago
11 months to 17months	y	a year ago
18months+	yy	2 years ago ... 20 years ago

Also, added from to toNow APIs.

Should we come up a new name for this plugin, since it's not only fromNow now

[codecov-io]

Codecov Report

Merging #189 into master will not change coverage.
The diff coverage is 100%.

@@          Coverage Diff          @@
##           master   #189   +/-   ##
=====================================
  Coverage     100%   100%           
=====================================
  Files          15     15           
  Lines         297    308   +11     
  Branches       50     52    +2     
=====================================
+ Hits          297    308   +11

Impacted Files	Coverage Δ
src/locale/es.js	100% <ø> (ø)	⬆️
src/plugin/fromNow.js	100% <100%> (ø)	⬆️

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[aalises]

Hi! Thank you very much for your work! It indeed is better that way. When I designed the plugin I had timeago.js in mind and a very basic approach to it, not as complex as moment.js

[iamkun]

Thanks @aalises.

Any review here?