Validate call

[Eeems]

There should probably be a method to validate current configuration:

• valid JSON
• All fields have correct data types
• No fields are missing
• No extra fields
• all registered files exist

[Eeems]

I think this would be good to add so that toltec can take advantage of it on reenable or install/upgrade of the package to provide some feedback to the user on what is happening if their templates all disappear due to bad data.