Refactor CollectInterestingnessData into CollectPhotosData
Add processing activity of any photo (non explored)
Minor changes and bug fixes
In scripts add collecting dat aabout any photos one month after they
were posted (run-stat-anyphoto-1monthago.sh)
Distrib of photos by owner's nb of photos and nb of contacts is now
generated into ActivityStat instead of UserStat.
All activity statistics is now produced in one single file: explored
photos, all photos one day old, all photos one month old