Install lxc-templates on Dwellers

Summary:
There is a series of templates to provision OS as lxc container
provided by the lxc project:

https://github.com/lxc/lxc/tree/master/templates

It's not shipped as a part of lxc in CentOS, but as a standalone package.

Test Plan: Applied state, got lxc-templates 1.0.9-1.el7 installed

Reviewers: dereckson

Reviewed By: dereckson

Differential Revision: https://devcentral.nasqueron.org/D983