FR: additinal parameter needed - ignore missing secret prefix path (with vault)

Hi

Is there possibility to continue `envconsul` working with `vault`, even if secret path is missing in vault?
same behavior like against consul (when prefix is missing it continue working and start the app) ?.

If not, can you add this functionality, so apps can always asks for same paths schema (`--secret properties/app/common` and `--secret properties/app/`).
If one of the path is missing - continue working - just provide what it has.