Make shivs output a little more informative

[Imaclean74]

Just a couple of things that could make the usage experience a little better ;

• Confirmation that an output file was written. ie generated pyz to <output_file> or similar
• Flagging of success vs some error condition. I was getting an error for a while - but wasn't entirely sure if it was just a warning - since the last output line is just "done".

If there is agreement that this would be useful I'm happy to put a quick PR together.

[lorencarvalho]

Confirmation that an output file was written. ie generated pyz to <output_file> or similar

This would be a welcome addition. Perhaps instead of just "done!" the confirmation could go here?

Flagging of success vs some error condition. I was getting an error for a while - but wasn't entirely sure if it was just a warning - since the last output line is just "done".

Proper exit codes should be being set (via sys.exit)... Curious what the specific error you ran into was, because "done" should indicate that the pyz was built successfully.

[Imaclean74]

aah - right you are - it didn't output done. Apologies - perhaps I was expecting a more forceful "Failed" error message.

[Imaclean74]

finally got around to making the merge request.

[Imaclean74]

@sixninetynine - I wonder if you could take a look at https://github.com/linkedin/shiv/pull/47 when you get a chance ?