Add Belarusian localization

[ilyankou]

#19

[hustcc]

Thank you for your work, because of the complex of be locale, so add some testcase into tests/test.js will be perfact. like this:

// 1. Test be locale
  // test second
  t.equal(timeago('2016-06-23 12:12:12').format('2016-06-23 12:12:09'), 'just now');
  // test second
  t.equal(timeago('2016-06-23 12:12:12').format('2016-06-23 12:12:01'), '11 seconds ago');

  // test minute
  t.equal(timeago('2016-06-23 12:11:12').format('2016-06-23 12:10:01'), '1 minute ago');
  t.equal(timeago('2016-06-23 12:12:12').format('2016-06-23 12:09:01'), '3 minutes ago');

  // test hour
  t.equal(timeago('2016-06-23 13:12:12').format('2016-06-23 12:10:01'), '1 hour ago');
  t.equal(timeago('2016-06-23 15:08:12').format('2016-06-23 12:09:01'), '2 hours ago');

  // test day
  t.equal(timeago('2016-06-24 13:12:12').format('2016-06-23 12:10:01'), '1 day ago');
  t.equal(timeago('2016-06-25 15:08:12').format('2016-06-23 12:09:01'), '2 days ago');

  // test week
  t.equal(timeago('2016-06-30 13:12:12').format('2016-06-23 12:10:01'), '1 week ago');
  t.equal(timeago('2016-07-18 15:08:12').format('2016-06-23 12:09:01'), '3 weeks ago');

  // test month
  t.equal(timeago('2016-07-25 13:12:12').format('2016-06-23 12:10:01'), '1 month ago');
  t.equal(timeago('2016-08-23 15:08:12').format('2016-06-23 12:09:01'), '2 months ago');

  // test year
  t.equal(timeago('2017-06-23 13:12:12').format('2016-06-23 12:10:01'), '1 year ago');
  t.equal(timeago('2020-06-23 15:08:12').format('2016-06-23 12:09:01'), '4 years ago');

  // end be locale test ---------------------------------------------------------

just translate en to be, and append into tests/test.js will be ok.

After do that, I will process this pr, thank you very much~

[likerRr]

@ilyankou take a look at #35

[likerRr]

@ilyankou sorry, but your test don't cover all possible cases (e.g. "5 хвiлiн таму"). Please, update them. And I think it would be better to keep them separately because it's gonna be mess when all the test are in one file. @hustcc , what do you think?

[hustcc]

@likerRr keep them separately will be more tidy. Very nice work^_^~

I will rewrite en and zh_CN into separated test files.

[hustcc]

@likerRr I push a commit 8e30c74, separate en and zh_CN into another file.

And in tests/test.js, read locale name from tests/locales, and require the testcase.

Thank you very much~