[#77896146] Fix mms-agent-backup upgrade issue

- Gleaned from https://github.com/edelight/chef-mongodb/blob/master/recipes/mms_backup_agent.rb
[#77896146] Fix mms-agent-backup upgrade issue

- Using newer conf file variable (2.4.0)
[#77896146] Fix mms-agent-backup upgrade issue

- Bump version to newest
[#77896146] Fix mms-agent-backup upgrade issue

- Bump version
[#77896146] Added tests

- Bump chefspec, berkshelf and other dependencies
- Will start running these specs during cibuild in another ticket
[#77896146] Remove cruft
Merge pull request #13 from Kabam/backup_agent_upgrade_fix

[#77896146] Fix mms-agent-backup upgrade issue