aravind process (filter + change_people templates)

Here is the basic functions templates that need to feed filter() and change_people()
Needs to be declined at the district level (match district of people --> structure he will attend), I sent it to Thibault to see if he agrees and complete it. Also need aggregate function that use these small functions in the right process order.
If you have time you can have a look at it so that tomorrow we work on how to integrate it in the existing environment in a clean way.