Activate storeconfigs on lizard's puppet master

Exported resources are handful and could be used in part of our puppet recipes, e.g to refactor our nfs shares.

But for them to work, our puppet master needs to have the `storeconfig` option activated, which seems not possible until the new `puppetdb` storage engine is packaged in Debian Jessie.

This is https://bugs.debian.org/673515, but it seems to need care.

Original created by @bertagaz on 8433 (Redmine)