Refactor peach-config to panic on error

[mhfowler]

No description provided.

[mhfowler]

now that peach-config is also handling updating, perhaps panicing on any error isn't the best.

A more nuanced solution might be to pass a flag that says "panic_on_error=True" when building the image only,
so when we are building and image we panic on any error,
but in the Real World we try to keep going

for now though leaving this as is