add support to take backups from PostgreSQL databases

[pmereddy]

Description: Created an ansible playbook to take backup of PostgreSQL databases and pull them to the local server

Usage:

1. Review and update the list of databases to backup in vars.yml
2. Update hosts field in pgsql_bkp.yml file to point to the ansible section that points to the PostgreSQL database host
3. If you want to pull the backupsto your local server, set fetch_local to true in vars.yml
4. ansible-playbook -u root -k ./pgsql_bkup.yml -i <ansible hosts file generated using utilities/nodes.py>

[pmereddy]

@Chaffelson : I have made the changes you have requested.

[Chaffelson]

@pmereddy can you please rebase this and I'll merge it.

[Chaffelson]

@pmereddy Can you please fix your commit tree here