Cache Driver - Backup Never Loaded
The condition that checks to see if the backup driver input is valid was prefixing the input with "cache_". Since the valid driver values don't have this prefix, the condition was always returning FALSE and the backup drivers were never being loaded.
I've removed the prefix in the condition and added a debug log message for when the backup driver is used.
Merge pull request #2555 from refringe/develop

Cache Driver - Backup Never Loaded