Update Let's Encrypt configuration for webserver-core role

Summary:
Create /usr/local/etc/letsencrypt directory if needed,
so the state works even if no config dir has been created.

Update to the API v2.

Test Plan: Deploy to web-001

Reviewers: dereckson

Reviewed By: dereckson

Differential Revision: https://devcentral.nasqueron.org/D3002