Symlinking on deploys & Rollback functionality

[AdamHebby]

My IDE also removes tailing spaces, which ansible-lint also classifies as an invalid thing

Anyway.

Changes:

• Adds 3 states of the web: new, current (symlinked to new), old
• Reduces downtime by moving service stop to last possible moment, right before the symlink
• Adds Rollback functionality & new playbook to do so

Tests:
Ideally, this would be tested on a real server, but I don't think that's possible?

Issues fixed:
#7
#3

[clone1018]

Sorry for the delay in review this, we've actually been using it in production for a bit :)

It's a great change, thank you for working on it! The one problem I noticed is old deploys are not being cleaned up like they should be. Let me know if you need help debugging!