Ability to specify multiple static folders

Fixes #258

Few things worth mentioning:
- For compatibility issues, we perform isArray check to provide fallback for old config files
- We still use the default method getPath, which allows us to specify the value as a second argument. To do so, the first string has been left as "unsupported" - subject to change. Can be considered in a future to be fullu rewritten to allow multiple paths for literally everything :)