Remove old disabled bytes test script
Simplify scrub_py2_stdlib_modules()
Clean up tests

* And remove the libfuturize/test_scripts dir that isn't currently used
Make ``futurize`` add ``standard_library.install_hooks()``
libfuturize: Add more diagnostic info about undecipherable imports

Thanks for Mike Dewhirst for the patch.
Remove extra newline after install_hooks() line