Review and revamp Ansible roles

* Completely reviewed the OS, Redis, Nginx, and App Ansible roles.
* Revamped Ansible roles to bring it more or less equal to Chef cookbooks.

Updated README file.

Modified Ansible inventory for staging environment.

Added missing group variables for App.

Update README.md

Removed Vagrantfile for building Ansible Tower.

Changed Ansible roles path.

Added .gitattributes file.

Updated Ansible configuration.