Integration with Social activity stream

[pnedonosko]

eXo Social cannot show cloud files preview properly as it doesn't rely on an UI component config and loads templates directly by the target node type, which is nt:file, it also doesn't rely mixins of the node. All this leads to use of default viewer which don't know how to get the remote content and as result shows empty file and its thumbnails. About tumbnails service need implement such support respecting what cloud provider provides (e.g. Google offers thumbnail link for a file).
Another problem that sym-links preview doesn't work due to logic in Social integration project, it relies also on primary nodetype of the node and doesn't recognize exo:symlink as a link, thus cannot find a template for it at all. Need consult with ECMS/PLF teams.