This reverts commit 451cb5006d35c5dba88177f97445f3cbca0b765b.

In a some systems, it is needed to install native library additionally.
So, now I think it is need to be thought again a bit more carefully.

Yona support social login, Github and Gmail.
It doesn't need to sign up anymore.

This feature was easily developed thanks to "Play Athenticate"
See: https://github.com/joscha/play-authenticate

Before:
xss.js with jvm javascript engine

After:
OWASP Java HTML Sanitizer
https://www.owasp.org/index.php/OWASP_Java_HTML_Sanitizer_Project

Reason:
xss.js is too buggy and not maintained anymore.

To increase performance and use more options,
upgrade MariaDB connector to v1.5.5

You can see available options and discussions:
https://mariadb.com/kb/en/mariadb/about-mariadb-connector-j

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.

eg.
YONA_DATA=/yona-data;export YONA_DATA
bin/yona

It will make easy to upgrade and backup
YONA_HOME is no longer needed.