use stderr instead of stdout for error messages

[czue]

This makes it easier to programatically access these (which is used by commcare sync)

[ctsims]

Looks like a strong change to me.

nit: I have 0 horses in this race, but I think the 'pythonic' way to print to stderr is print("message", file=sys.stderr) Not sure if the HQ team has an explicit preference.

[czue]

I think the 'pythonic' way to print to stderr is print("message", file=sys.stderr)

I had just copied it from elsewhere in the file but that does seem better. let me test/update

[millerdev]

Agree on print(..., file=sys.stderr)

[czue]

updated @millerdev @ctsims