Determine the package name when uploading to PyPI

* modules/jenkins/files/slave_scripts/pypi-extract-name.py: Short
new script to safely parse the sdist package name out of a setup.cfg
file.

* modules/jenkins/files/slave_scripts/pypi-upload.sh: Subsume the
guts of the first shell builder from the pypi-upload job, extended
to call pypi-extract-name.py and fall back to the name of the Git
project if it fails--this is needed for cases where those names
differ, for example in capitalization.

* .../jenkins_job_builder/config/pypi-jobs.yaml: Clone and checkout
the Git tag which triggered this upload to PyPI, and then only call
the modified pypi-upload.sh script since it should now analyze the
state of the setup.cfg to determine how to retrieve the
corresponding tarball.

Change-Id: I43843e6e74b918e9c68f4b27958ec605774668ff
Merge "Determine the package name when uploading to PyPI"