integrated PostHandler mechanism into Post (server)
Merge remote-tracking branch 'origin/master' into restructure-post-handler
added documentation for WallApp.add_post_type
added remote class to remote template
simplified general post style (remote)
integrated PostHandler mechanism into PostElement (client)

introduced (UI) element architecture and applied it to posts (client)
changed ImagePostElement to use background instead of img (display)
Merge pull request #86 from NoyaInRain/restructure-post-handler

Restructure Post Handler