`config/bundles.yml` was removed in RedHatInsights/entitlements-config#51 ,
leading to a 404 on the `/api/entitlements/v1/services` local endpoint (caused by `fs.readFileSync` throwing).

Changing to use `configs/stage/bundles.yml` (`prod` also being an option),
except the original yaml data is hidden as a yaml string field inside `objects[0].data['bundles.yml']` in that file.

… field

without this, if the handler throws, webpack acts as if the endpoint didn't exist, returning a 404, making debugging harder

this makes the error more explicit

Fix standalone entitlements 404, add error handling

…to 1.5.17

Bump config utils version.