Compatible with Redmine 2.3.x

* prototype.js -> jQuery Conversions.
* rhtml -> erb
* Rails3 html_safe
* Fixed Compatible with Redmine 2.3.x

ref http://www.redmine.org/issues/13753
ref https://github.com/krishnasrihari/redmine_favicon/commit/ef46eeb70eed2fd59d76a01c1bb9e4f2dcd62b55