Fix express deprecation warning for app.del
Fix express deprecation warning for app.del

Fixes the following warning:

    express deprecated app.del: Use app.delete instead

openstate/popit,Sinar/popit,mysociety/popit,mysociety/popit,Sinar/popit,openstate/popit,mysociety/popit,mysociety/popit,openstate/popit,openstate/popit,mysociety/popit,Sinar/popit,Sinar/popit