Instead of YONA_HOME, use YONA_DATA.
If you set a YONA_DATA and run bin/yona,
conf, uploads, repos, logs will be stored at YONA_DATA folder.
It will make easy to upgrade and backup
YONA_HOME is no longer needed.
Problem: Customizing application-logger.xml was quite difficult because the file
may be overwritten by updating Yobi.
* Rename conf/application-logger.xml to
conf/application-logger.xml.default not to overwrite user's file.
* Generate conf/application-logger.xml if it doesn't exist by copying from
conf/application-logger.xml.default when Yobi starts.