Provide simple statistics for logged in user

[kleinfe]

For his own data display like:

• Number of views
• Number of downloads
• ...?

From the discussion with Mr. Todoroki

[bastiensaquet]

Requested by NIMS

[natasab]

Proposal:
these kind of statistics in fact can be implemented by a "social activity" component, which then can be used not only for actions of type who viewed what, who downloaded what, but also for actions of type "who changed what to what" , "who created which collection" etc etc..

This could serve as a "lazy" history of the resource (well, not versioning indeed, but rather provenance info)