make-release: Actually use the logging module

The script had arguments like --debug and --quiet, but nothing
actually used them.

Information about what the script was going to do were converted
to debug statements (not displayed by default). Things the script
had completed are at info level (displayed by default, quietable).
All errors are at error level.

I left the ask function and the email template as print statements
since those should always go to stdout.

Finally, this should make the transition to python3 easier.

Change-Id: I5e9d4b4ecc17595846d9764def733deec8f992b7