Ansible 2.4 changes the way includes work. Now you have to use "import"
for playbooks and tasks that are static, and "include" for those that
are dynamic (ie, those that use variables, loops, etc).
See: http://docs.ansible.com/ansible/devel/playbooks_reuse_includes.html
For idempotence we need to run all apt-related tasks, like editing
source files, adding keys, installing packages, etc, when running
the 'packages' tag.
Instead of using dynamic hack to use the package manager for the
current host. We only have Ubuntu here anyways.
Signed-off-by: Alan Orth <alan.orth@gmail.com>