Changing the permission of one file to non-readable would cause drift to stop. This stoppage however does not make it to the user level, but instead it fails silently. 

In addition the entire drift should not stop just because the agent cannot read a single file. Instead it should just skip over that file and continue to detect drift on other readable files.

To reproduce:
- Create a file drift and point to a readable folder
- Create two files in that folder and verify that both files show up in drift history.
- Change permission of one of the file to non-readable state
- Make modification to the other file.
- Verify that no error message occurs in RHQ UI
- Verify that the modification on the second file does not show up on drift history.