Update packages on ubuntu and freebsd

Fixes #1

The Vagrant file being used is a copy from
`https://github.com/stationgroup/vagrant-labs/tree/master/imperialspeculate`.

Two roles are being used: debian-upgrade (an upstream Galaxy role) and
freebsd-upgrade (a small role based on what was proposed in the comments of #1
and extended with proper support for check mode.)

The upgrade process is contained in the playbook os_upgrade.yml, which will
automatically create proper groups for Ubuntu and FreeBSD hosts. If unneeded,
this first play can be left out, and the target hosts: in the second play can be
replaced by the relevant groups you have in the inventory (e.g. ec2 tags.)

A local ansible.cfg is defined, and needed for these scripts to run out of the
box. This implies that all ansible commands must be run from the
`ansible-experiments/package_updates` folder.

A small script `setup-requirements` is provided, that initializes everything,
to be executed after the vagrant boxes came online. It will generate an
ssh-config for said vagrant boxes, download roles from galaxy, and make a
base-install for the hosts (installing python dependencies, ansible itself
on ubuntu1, a deploying an ssh key to all nodes to be used from the vagrant box
`ubuntu1`, as ansible controller machine.)

When deploying and setting up from the machine where vagrant runs, you need to
add some extra arguments:
`--ssh-extra-args "-F ./vagrant-ssh-config" --inventory hosts-vagrant`
to ansible execution. These are not necessary once running ansible from
`ubuntu1`.

The vagrant setup seems to have a provisioning bug, that kicks in with the
latest 18.04 Ubuntu. The FreeBSD boxes also experience a provisioning problem,
with the same result: the second, private network interface does not get
configured. As these interfaces are used to run ansible from `ubuntu1`, I could
not fully test the scripts from there.

package_updates/roles/freebsd-update/tasks/main.yml

@@ -0,0 +1,35 @@
+---
+- name: Fetch any new FreeBSD updates
+  command: freebsd-update fetch --not-running-from-cron
+  check_mode: no
+  when: ansible_distribution == 'FreeBSD'
+  register: result_update
+  changed_when: "'No updates needed' not in result_update.stdout"
+
+- debug: var=result_update
+  when: result_update.changed
+
+- name: Install FreeBSD updates
+  command: freebsd-update install --not-running-from-cron
+  when: ansible_distribution == 'FreeBSD' and result_update.changed and not ansible_check_mode
+  register: result_update_install
+
+- debug: var=result_update_install
+  when: result_update_install.changed
+
+
+- name: Upgrade FreeBSD packages - dry-run
+  command: pkg upgrade --dry-run
+  check_mode: no
+  when: ansible_distribution == 'FreeBSD' and ansible_check_mode
+  register: result_pkg
+  changed_when: "'Your packages are up to date' not in result_pkg.stdout"
+
+- name: Upgrade FreeBSD packages
+  command: pkg upgrade --yes
+  when: ansible_distribution == 'FreeBSD' and not ansible_check_mode
+  register: result_pkg
+  changed_when: "'Your packages are up to date' not in result_pkg.stdout"
+
+- debug: var=result_pkg
+  when: result_pkg.changed