Support reloading of rules in a directory

[gmenuel]

Currently we can load access rules from a directory by setting the access rules repository to something like file:///etc/oathkeeper-rules/ (I'm not sure this is intended because it doesn't seems to be documented). However Oathkeeper doesn't reload the rules in the repository (it doesn't detect new files, and it doesn't reload when an existing file is updated).

Having this feature would allow us to use Oathkeeper in a k8s cluster with dynamic access rules set in configmap with the help of https://github.com/kiwigrid/k8s-sidecar

[aeneasr]

This is not an intended behavior and we'll remove the possibility to reference a whole directory, also because it might be a security issue in cases where not all config files files in a directory should be read/respected. Thank you for the report!