Vietnamese Translations added to FAMods

Thanks to @tuananh88c25, Vietnamese Install language files are now committed in my unofficial GitHub Repo and are available at:
https://github.com/apmuthu/frontaccounting/tree/master/FAMods/install/lang/vi_VN

Transifex now has Vietnamese added for FrontAccounting v2.3.x with 1% of the strings translated for now and @tuananh88c25 has been added as a translator at:
https://www.transifex.com/gnuacademy/frontaccounting-1/language/vi_VN/

The Vietnamese core translation files are available at:
https://github.com/apmuthu/frontaccounting/tree/master/extensions/Languages/vi_VN

These files can now be added to the official translation as a pkg file.