Update jquery.i18n from upstream

Upstream: https://github.com/wikimedia/jquery.i18n
Upstream changes:
* Fixed a potential js error because of wrong logic
* Fixed some JShint errors
* Added license and credits files
* Updated gitignore file
* Fixed uk and ru grammar rules and updating tests
* Source code formatting updates

Change-Id: I43433cc3d9993045160dc85ed9e73370d22794cf