Small log improvements

[JSCU-CNI]

This PR addresses two small issues:

• The hash record modifier could generate a lot of warnings when combining the walkfs plugin with --hash as a lot of files can be broken. this log is now demoted to INFO for FileNotFoundErrors as that exception is not really interesting in those instances.
• When entering a child target using --children or target-shell's enter the path of said child was appended to the locations of where to look for targetcfg files. That obviously does not work as that path is virtual inside the main target. This is now fixed.