added xe-core

this is common js, css, mp3(for sound captcha), swf, png, jpg, gif(for default image button, etc..) of xe-core(Xpressengine).

if there is not minified version of js or css, that means combined and minified version is exist.
ex) in common/js directory
xe.min.js  == (minified)[ common.js + js_app.js + xml_handler.js + xml_js_filter.js ]

in normal status, xe-core loads only minified and combined js and css file for performance.
not combined or not minified file is loaded only when xe-core is in debug mode(set by developer).

i set auto update for .js .css .swf .jpg. jpeg .png .gif
https://github.com/xpressengine/xe-core
http://www.xpressengine.com (offcial site, Korea)

License : LGPLv2