add AvatarPicker and profile tab
1. optimise ConnectionManager by Defer
2. add DeferHelper
1. sendFile by xmpp file transfer
2. call SmackAndroid.init() to init register of Providers
add xUtils src
implement upload file
1. put Db operation in seperate thread
2. modify sendMessage to use Defer
1. fix ExMsgFileProvider
2. fix doSendMsgForFile