Trouble using b2 backends without upgrading duplicity

[apmarshall]

I ran into an issue where backups to b2/backblaze were failing with a 404 error in the BKP step. After doing some research, discovered that this is a known issue that was fixed in duplicity 0.7.07. Unfortunately, the default in Ubuntu Trusty is 0.7.06. To upgrade, we need to add a new apt repo and then upgrade the package. As this is specific to the OS used in Trellis, I thought it better to include those steps in this plugin rather than in lafranceinsoumise/ansible-backup. Pull request coming momentarily with a suggested fix.

[jillro]

This is fixed in https://github.com/lafranceinsoumise/ansible-backup.