Add path and size information to health check

TODO: This has just revealed a horrible problem with the config
object; in that the defaults are computed in the backgrond thread
which is a separate process from the frontend -- meaning the frontend
has no clue what the backend did to the config options. Solution: always
set paths statically in the config file...

Change-Id: Icd8c6d43eb1ba57b75b70c3d63c14212a4f3ea8a