https://github.com/igniterealtime/Smack/wiki/Smack-XMPP-File-Transfer
http://wiki.jabbercn.org/XEP-0065
http://wiki.jabbercn.org/XEP-0096
http://www.apkbus.com/android-162731-1-1.html
http://blog.csdn.net/jwzhangjie/article/details/12171825
http://blog.csdn.net/jdcdrdim/article/details/7255083
http://www.process-one.net/docs/ejabberd/guide_en.html#htoc55