Fix #476 Auto language changing function finished.

Fixes issue#476.
If the user does not have the freeseer.conf file, the function will detect the system location for default language.
If there is a config file, the language setting in that file will have higher priority.
For Chinese, If the location is not zh_CN, Traditional Chinese will be used.
If there is no translation for the system location, English will be used.
I recall we already had a discussion on ja vs ja_JP and I thought we already confirmed that "ja" was the correct reporting from the OS. See log from https://botbot.me/freenode/freeseer/2014-10-19/?msg=23775576&page=1