improve granularity of printed time

[shime]

although I appreciate @marceloboeira's efforts in #69, I don't like
how imprecise the printed time becomes.

to demonstrate, this is how ms converts miliseconds

var time = require('ms')

time(2000)    // '2s'
time(62000)   // '1m'
time(3662000) // '1h'

and this is how humanize-time does it

var time = require('humanize-time')

time(2000)    // '2s'
time(62000)   // '1m, 2s'
time(3662000) // '1h, 1m, 2s'

[marceloboeira]

@shime my only worry is about position on the screen of this humanize time, but if works its really good stuff.

[lbeschastny]

👍

[micky2be]

👍

[IgorNadj]

I don't see a reason why this shouldn't be the output of the default :eta flag (rather than adding a separate flag).