Create DB script: rename fk column

- ecole -> ecole_id
Create DB script: add 'v_classes' view
Update Mailchimp API to dev-master

Fix PHP NOTICE: Undefined index: CURLOPT_FOLLOWLOCATION
in /src/Mailchimp.php, line 158
Create DB script: add missing fields to familles table
Create DB script: new view v_mc_enfants
Data insertion script

This script contains SQL statements to populate the base tables with
data from the mailchimp staging table.