Create playbook for updating our Linux nodes

[robertapplin]

This PR creates an ansible playbook for updating our Linux nodes. It uses a useful role already defined in a Dan Nixon repo.

To test

1. ssh into a linux node (not the first linux node as this has already been updated)

ssh <username>@<node_ip_address>

2. Check there is a message that at least 1 package needs updating
3. Exit the machine
4. Create an inventory.txt file in your ansible directory containing the details of this node
5. Run the following playbook

   ansible-playbook -i inventory.txt update.yml -u SSH_USERNAME -K

6. ssh back into the linux node. Make sure there are no more updates.

Fixes #87

[thomashampson]

I've run the ansible-playbook command but it has skipped the reboot:

TASK [dannixon.system.package_updates : Ensure system is rebooted] **********************************************************************
skipping: [ip address was here]

but when i log back into the machine it says: *** System restart required ***

[robertapplin]

but when i log back into the machine it says: *** System restart required ***

That is odd, I assume there was at least one package update to be made?

[thomashampson]

but when i log back into the machine it says: *** System restart required ***

That is odd, I assume there was at least one package update to be made?

On first login it said:

2 updates can be applied immediately.

10 additional security updates can be applied with ESM Apps.
Learn more about enabling ESM Apps service at https://ubuntu.com/esm

*** System restart required ***

than after running the playbook it said:

0 updates can be applied immediately.

10 additional security updates can be applied with ESM Apps.
Learn more about enabling ESM Apps service at https://ubuntu.com/esm

*** System restart required ***