user_follow table auto-clean

[Helias]

we have to add a timestamp field in the user_follow table and clean after 1 year (or less?) the user_follow table, because no-one will unfollow a spot after several months but the data will remain in the db, the db could become bigger and bigger in the years and it's better to clean it automatically.

adding the timestamp it's easy using some alter table and TIMESTAMP as field name and value
adding the auto-clean consists of implementing a daily-job that deletes all the user_follow with X time ago where X should be a configurable variable in terms of months (12 months? 6 months?)

[Helias]

similarly, we can apply this for the reports