Cleanups after new changes/features.

- Some style adjustments.
- Use SRC_REPOS for mapping repo name to source repository name.
- Split the build_binary into individual tiny functions.
- Fix up the progress bars and iterable logging.
- Ensure that we log that we wrote to /etc/yum.repos.d and leave a trace for later cleanup.
- Quiet some of the new executes (and put there output to files).
- Add a smithy clean_pip() function that will help avoid hitting https://github.com/pypa/pip/issues/982
- Further cleanup of smithy after it being partially rewritten.
- Instead of hard coding 'conf/distros/rhel.yaml' in smithy, take this from the sourced file.
- Ensure that we can't remove packages smithy requires to operate.
- Ensure the package version that py2rpm is building is also trimmed of zeros.

Change-Id: I2df8a47f0115de2684777b64db42e08d50ef4115