util-app: Improved critical messages

Ensure path of the file, that we failed to read is included in the
messages.

https://bugzilla.gnome.org/show_bug.cgi?id=729345
util-app: Turn 2 criticals into warnings

These messages are not severe enough to be criticals.

https://bugzilla.gnome.org/show_bug.cgi?id=729345