Testing Integration and Logging Enhancement

[epeguero]

Note to self (& @epeguero) for after this PR is merged: there are a few things that would be cool to try cleaning up in the gluer implementation, now that we have tests that can automatically check whether we broke anything!

• Use a proper argument parser.
• Print output to stdout by default (if -o is omitted). This will make the Turnt setup easier.
• As part of that, print logging stuff to stderr. (Perhaps using logging.)

Originally posted by @sampsyo in #28 (comment)