Feature: Add deploy info to a log file

[mamedin]

We were using in the shared sites' playbook this task:

     - name: "Update deploy log"
       become: "true"
       blockinfile:
         path: "/var/log/atom-deploy.log"
         insertafter: EOF
         marker: "-------"
         create: true
         content: |
           Installed {{ site }} on {{ ansible_ssh_host }}
           Revision: {{ latest_revision.stdout }} ( {{ atom_repository_version }} )
           Run by: {{ tower_user_name | default(lookup('env', 'USER')) }}
           Current date is: {{ ansible_date_time.iso8601 }}
       tags: "always"

Could be useful something like this for AWX and non AWX deploys.